Tropical Fish – Species

Definition

Classification

Fish are classified into the following major groups:

Anatomy

Fish anatomy

Digestive system

Respiratory system

Circulatory system

Excretory system

Sensory and nervous system

Muscular system

Reproductive system

Organs

Reproductive method

Immune system

Evolution

Homeothermy

Diseases

Importance to humans

Economic importance

Recreation

Overfishing

Habitat destruction

Exotic species

Aquarium collecting

Culture

Plural forms

History and popularization

Design

Materials

Styles

Components

Aquarium classifications

Public aquarium

Tropical Fish – Species

 

Fish are aquatic vertebrates that are cold-blooded, Portsmouth Tropical Fish covered with scales, Portsmouth Tropical Fish and equipped with two sets of paired fins and several unpaired fins. Fish are abundant in the sea and in fresh water, Portsmouth Tropical Fish with species being known from mountain streams (e.g., Portsmouth Tropical Fish char and gudgeon) as well as in the deepest depths of the ocean (e.g., Portsmouth Tropical Fish gulpers and anglerfish).

 

They are of tremendous importance as food for people around the world, Portsmouth Tropical Fish either collected from the wild (see fishing) or farmed in much the same way as cattle or chickens (see aquaculture). Fish are also exploited for recreation, Portsmouth Tropical Fish through angling and fishkeeping, Portsmouth Tropical Fish and fish are commonly exhibited in public aquaria. Fish have an important role in many cultures through the ages, Portsmouth Tropical Fish ranging as widely as deities and religious symbols to subjects of books and popular movies.

A giant grouper at the Georgia Aquarium, Portsmouth Tropical Fish seen swimming among other schools of fish

A giant grouper at the Georgia Aquarium, Portsmouth Tropical Fish seen swimming among other schools of fish

Contents

 

    * 1 Definition

    * 2 Classification

    * 3 Anatomy

          o 3.1 Digestive system

          o 3.2 Respiratory system

          o 3.3 Circulatory system

          o 3.4 Excretory system

          o 3.5 Sensory and nervous system

          o 3.6 Muscular system

          o 3.7 Reproductive system

                + 3.7.1 Organs

                + 3.7.2 Reproductive method

          o 3.8 Immune system

    * 4 Evolution

    * 5 Homeothermy

    * 6 Diseases

    * 7 Importance to humans

          o 7.1 Economic importance

          o 7.2 Recreation

    * 8 Conservation

          o 8.1 Overfishing

          o 8.2 Habitat destruction

          o 8.3 Exotic species

          o 8.4 Aquarium collecting

    * 9 Culture

    * 10 Plural forms

    * 11 See also

    * 12 References

          o 13.1 Taxonomy

          o 13.2 Biogeography

          o 13.3 Ichthyology

 

Definition

 

The term "fish" is most precisely used to describe any non-tetrapod chordate, Portsmouth Tropical Fish i.e., Portsmouth Tropical Fish an animal with a backbone that has gills throughout life and has limbs, Portsmouth Tropical Fish if any, Portsmouth Tropical Fish in the shape of fins.Unlike groupings such as birds or mammals, Portsmouth Tropical Fish fish are not a single clade but a paraphyletic collection of taxa, Portsmouth Tropical Fish including hagfishes, Portsmouth Tropical Fish lampreys, Portsmouth Tropical Fish sharks and rays, Portsmouth Tropical Fish ray-finned fishes, Portsmouth Tropical Fish coelacanths, Portsmouth Tropical Fish and lungfishes.[2][3]

 

A typical fish is cold-blooded; has a streamlined body that allows it to swim rapidly; extracts oxygen from the water using gills or an accessory breathing organ to enable it to breath atmospheric oxygen; has two sets of paired fins, Portsmouth Tropical Fish usually one or two (rarely three) dorsal fins, Portsmouth Tropical Fish an anal fin, Portsmouth Tropical Fish and a tail fin; has jaws; has skin that is usually covered with scales; and lays eggs that are fertilized internally or externally.

Fish come in many shapes and sizes. This is a sea dragon, Portsmouth Tropical Fish a close relative of the seahorse. Their leaf-like appendages enable them to blend in with floating seaweed

Fish come in many shapes and sizes. This is a sea dragon, Portsmouth Tropical Fish a close relative of the seahorse. Their leaf-like appendages enable them to blend in with floating seaweed

 

However, Portsmouth Tropical Fish to each of these there are exceptions. Tuna, Portsmouth Tropical Fish Swordfish, Portsmouth Tropical Fish and some species of sharks show some warm-blooded adaptations, Portsmouth Tropical Fish and are able to raise their body temperature significantly above that of the ambient water surrounding them.[4] Streamlining and swimming performance varies from highly streamlined and rapid swimmers which are able to reach 10-20 body-lengths per second (such as tuna, Portsmouth Tropical Fish salmon, Portsmouth Tropical Fish and jacks) through to slow but more maneuverable species such as eels and rays that reach no more than 0.5 body-lengths per second.[5] Many groups of freshwater fish extract oxygen from the air as well as from the water using a variety of different structures. Lungfish have paired lungs similar to those of tetrapods, Portsmouth Tropical Fish gouramis have a structure called the labyrinth organ that performs a similar function, Portsmouth Tropical Fish while many catfish, Portsmouth Tropical Fish such as Corydoras extract oxygen via the intestine or stomach.[6] Body shape and the arrangement of the fins is highly variable, Portsmouth Tropical Fish covering such seemingly un-fishlike forms as seahorses, Portsmouth Tropical Fish pufferfish, Portsmouth Tropical Fish anglerfish, Portsmouth Tropical Fish and gulpers. Similarly, Portsmouth Tropical Fish the surface of the skin may be naked (as in moray eels), Portsmouth Tropical Fish or covered with scales of a variety of different types usually defined as placoid (typical of sharks and rays), Portsmouth Tropical Fish cosmoid (fossil lungfishes and coelacanths), Portsmouth Tropical Fish ganoid (various fossil fishes but also living gars and bichirs, Portsmouth Tropical Fish cycloid, Portsmouth Tropical Fish and ctenoid (these last two are found on most bony fish.[7] There are even fishes that spend most of their time out of water. Mudskippers feed and interact with one another on mudflats and are only underwater when hiding in their burrows.[8] The catfish Phreatobius cisternarum lives in underground, Portsmouth Tropical Fish phreatic habitats, Portsmouth Tropical Fish and a relative lives in waterlogged leaf litter.[9][10]

 

Fish range in size from the 16 m (51 ft) whale shark to a 8 mm (just over ¼ of an inch) long stout infantfish.

 

Many types of aquatic animals commonly referred to as "fish" are not fish in the sense given above; see Fish (disambiguation).

 

Classification

 

Fish are a paraphyletic group: that is, Portsmouth Tropical Fish any clade containing all fish also contains the tetrapods, Portsmouth Tropical Fish which are not fish. For this reason, Portsmouth Tropical Fish groups such as the "Class Pisces" seen in older reference works are no longer used in formal classifications.

 

Fish are classified into the following major groups:

 

    * Subclass Pteraspidomorphi (early jawless fish)

    * Class Thelodonti

    * Class Anaspida

    * (unranked) Cephalaspidomorphi (early jawless fish)

          o (unranked) Hyperoartia

                + Petromyzontidae (lampreys)

          o Class Galeaspida

          o Class Pituriaspida

          o Class Osteostraci

    * Infraphylum Gnathostomata (jawed vertebrates)

          o Class Placodermi (armoured fishes, Portsmouth Tropical Fish extinct)

          o Class Chondrichthyes (cartilaginous fish)

          o Class Acanthodii (spiny sharks, Portsmouth Tropical Fish extinct)

          o Superclass Osteichthyes (bony fish)

                + Class Actinopterygii (ray-finned fish)

                + Class Sarcopterygii (lobe-finned fish)

                      # Subclass Coelacanthimorpha (coelacanths)

                      # Subclass Dipnoi (lungfish)

 

Some palaeontologists consider that Conodonta are chordates, Portsmouth Tropical Fish and so regard them as primitive fish. For a fuller treatment of classification, Portsmouth Tropical Fish see the vertebrate article.

 

The various fish groups taken together account for more than half of the known vertebrates. There are almost 28,000 known extant species of fish, Portsmouth Tropical Fish of which almost 27,000 are bony fish, Portsmouth Tropical Fish with the remainder being about 970 sharks, Portsmouth Tropical Fish rays, Portsmouth Tropical Fish and chimeras and about 108 hagfishes and lampreys.[11] A third of all of these species are contained within the nine largest families; from largest to smallest, Portsmouth Tropical Fish these families are Cyprinidae, Portsmouth Tropical Fish Gobiidae, Portsmouth Tropical Fish Cichlidae, Portsmouth Tropical Fish Characidae, Portsmouth Tropical Fish Loricariidae, Portsmouth Tropical Fish Balitoridae, Portsmouth Tropical Fish Serranidae, Portsmouth Tropical Fish Labridae, Portsmouth Tropical Fish and Scorpaenidae. On the other hand, Portsmouth Tropical Fish about 64 families are monotypic, Portsmouth Tropical Fish containing only one species. It is predicted that the eventual number of total extant species will be at least 32,500.[12]

 

Anatomy

 

    Fish anatomy

 

The anatomy of Lampanyctodes hectoris (1) - operculum (gill cover), Portsmouth Tropical Fish (2) - lateral line, Portsmouth Tropical Fish (3) - dorsal fin, Portsmouth Tropical Fish (4) - fat fin, Portsmouth Tropical Fish (5) - caudal peduncle, Portsmouth Tropical Fish (6) - caudal fin, Portsmouth Tropical Fish (7) - anal fin, Portsmouth Tropical Fish (8) - photophores, Portsmouth Tropical Fish (9) - pelvic fins (paired), Portsmouth Tropical Fish (10) - pectoral fins (paired)

The anatomy of Lampanyctodes hectoris

(1) - operculum (gill cover), Portsmouth Tropical Fish (2) - lateral line, Portsmouth Tropical Fish (3) - dorsal fin, Portsmouth Tropical Fish (4) - fat fin, Portsmouth Tropical Fish (5) - caudal peduncle, Portsmouth Tropical Fish (6) - caudal fin, Portsmouth Tropical Fish (7) - anal fin, Portsmouth Tropical Fish (8) - photophores, Portsmouth Tropical Fish (9) - pelvic fins (paired), Portsmouth Tropical Fish (10) - pectoral fins (paired)

 

Digestive system

 

The advent of jaws allowed fish to eat a much wider variety of food, Portsmouth Tropical Fish including plants and other organisms. In fish, Portsmouth Tropical Fish food is ingested through the mouth and then broken down in the esophagus. When it enters the stomach, Portsmouth Tropical Fish the food is further broken down and, Portsmouth Tropical Fish in many fish, Portsmouth Tropical Fish further processed in fingerlike pouches called pyloric caeca. The pyloric caeca secrete digestive enzymes and absorb nutrients from the digested food. Organs such as the liver and pancreas add enzymes and various digestive chemicals as the food moves through the digestive tract. The intestine completes the process of digestion and nutrient absorption.

 

Respiratory system

 

Most fish exchange gases by using gills that are located on either side of the pharynx. Gills are made up of threadlike structures called filaments. Each filament contains a network of capillaries that allow a large surface area for the exchange of oxygen and carbon dioxide. Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gill filaments. The blood in the capillaries flows in the opposite direction to the water, Portsmouth Tropical Fish causing counter current exchange. They then push the oxygen-poor water out through openings in the sides of the pharynx. Some fishes, Portsmouth Tropical Fish like sharks and lampreys, Portsmouth Tropical Fish possess multiple gill openings. However, Portsmouth Tropical Fish most fishes have a single gill opening on each side of the body. This opening is hidden beneath a protective bony cover called an operculum.

 

Juvenile bichirs have external gills, Portsmouth Tropical Fish a very primitive feature that they hold in common with larval amphibians.

Swim bladder of a Rudd (Scardinius erythrophthalmus)

Swim bladder of a Rudd (Scardinius erythrophthalmus)

 

Many fish can breathe air. The mechanisms for doing so are varied. The skin of anguillid eels may be used to absorb oxygen. The buccal cavity of the electric eel may be used to breathe air. Catfishes of the families Loricariidae, Portsmouth Tropical Fish Callichthyidae, Portsmouth Tropical Fish and Scoloplacidae are able to absorb air through their digestive tracts.[13] Lungfish and bichirs have paired lungs similar to those of tetrapods and must rise to the surface of the water to gulp fresh air in through the mouth and pass spent air out through the gills. Gar and bowfin have a vascularised swim bladder that is used in the same way. Loaches, Portsmouth Tropical Fish trahiras, Portsmouth Tropical Fish and many catfish breathe by passing air through the gut. Mudskippers breathe by absorbing oxygen across the skin (similar to what frogs do). A number of fishes have evolved so-called accessory breathing organs that are used to extract oxygen from the air. Labyrinth fish (such as gouramis and bettas) have a labyrinth organ above the gills that performs this function. A few other fish have structures more or less resembling labyrinth organs in form and function, Portsmouth Tropical Fish most notably snakeheads, Portsmouth Tropical Fish pikeheads, Portsmouth Tropical Fish and the Clariidae family of catfish.

 

Being able to breathe air is primarily of use to fish that inhabit shallow, Portsmouth Tropical Fish seasonally variable waters where the oxygen concentration in the water may decline at certain times of the year. At such times, Portsmouth Tropical Fish fishes dependent solely on the oxygen in the water, Portsmouth Tropical Fish such as perch and cichlids, Portsmouth Tropical Fish will quickly suffocate, Portsmouth Tropical Fish but air-breathing fish can survive for much longer, Portsmouth Tropical Fish in some cases in water that is little more than wet mud. At the most extreme, Portsmouth Tropical Fish some of these air-breathing fish are able to survive in damp burrows for weeks after the water has otherwise completely dried up, Portsmouth Tropical Fish entering a state of aestivation until the water returns.

Tuna gills inside of the head. The fish head is oriented snout-downwards, Portsmouth Tropical Fish with the view looking towards the mouth.

Tuna gills inside of the head. The fish head is oriented snout-downwards, Portsmouth Tropical Fish with the view looking towards the mouth.

 

Fish can be divided into obligate air breathers and facultative air breathers. Obligate air breathers, Portsmouth Tropical Fish such as the African lungfish, Portsmouth Tropical Fish must breathe air periodically or they will suffocate. Facultative air breathers, Portsmouth Tropical Fish such as the catfish Hypostomus plecostomus, Portsmouth Tropical Fish will only breathe air if they need to and will otherwise rely solely on their gills for oxygen if conditions are favourable. Most fish are not obligate air breathers as there is an energetic cost in rising to the surface and a fitness cost of being exposed to predators.[13]

 

Circulatory system

 

Fish have a closed circulatory system with a heart that pumps the blood in a single loop throughout the body. The blood goes from the heart to gills, Portsmouth Tropical Fish from the gills to the rest of the body, Portsmouth Tropical Fish and then back to the heart. In most fish, Portsmouth Tropical Fish the heart consists of four parts: the sinus venosus, Portsmouth Tropical Fish the atrium, Portsmouth Tropical Fish the ventricle, Portsmouth Tropical Fish and the bulbus arteriosus. Despite consisting of four parts, Portsmouth Tropical Fish the fish heart is still a two-chambered heart. [14] The sinus venosus is a thin-walled sac that collects blood from the fish's veins before allowing it to flow to the atrium, Portsmouth Tropical Fish which is a large muscular chamber. The atrium serves as a one-way compartment for blood to flow into the ventricle. The ventricle is a thick-walled, Portsmouth Tropical Fish muscular chamber and it does the actual pumping for the heart. It pumps blood to a large tube called the bulbus arteriosus. At the front end, Portsmouth Tropical Fish the bulbus arteriosus connects to a large blood vessel called the aorta, Portsmouth Tropical Fish through which blood flows to the fish's gills.

 

Excretory system

 

As with many aquatic animals, Portsmouth Tropical Fish most fish release their nitrogenous wastes as ammonia. Some of the wastes diffuse through the gills into the surrounding water. Others are removed by the kidneys, Portsmouth Tropical Fish excretory organs that filter wastes from the blood. Kidneys help fishes control the amount of ammonia in their bodies. Saltwater fish tend to lose water because of osmosis. In saltwater fish, Portsmouth Tropical Fish the kidneys concentrate wastes and return as much water as possible back to the body. The reverse happens in freshwater fish, Portsmouth Tropical Fish they tend to gain water continuously. The kidneys of freshwater fish are specially adapted to pump out large amounts of dilute urine. Some fish have specially adapted kidneys that change their function, Portsmouth Tropical Fish allowing them to move from freshwater to saltwater.

 

Sensory and nervous system

 

Fish have well-developed nervous systems, Portsmouth Tropical Fish but no brain, Portsmouth Tropical Fish that is divided into different parts. The most anterior, Portsmouth Tropical Fish or front, Portsmouth Tropical Fish end of the brain are the olfactory bulbs, Portsmouth Tropical Fish which are involved in the fish's sense of smell. Unlike most vertebrates, Portsmouth Tropical Fish the cerebrum of the fish primarily processes the sense of smell rather than being responsible for all voluntary actions. The optic lobes process information from the eyes. The cerebellum coordinates body movements while the medulla oblongata controls the functions of internal organs. Most fish possess highly developed sense organs. Nearly all daylight fish have well-developed eyes that have color vision that is at least as good as a human's. Many fish also have specialized cells known as chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears in their heads, Portsmouth Tropical Fish many fish may not hear sounds very well. However, Portsmouth Tropical Fish most fishes have sensitive receptors that form the lateral line system. The lateral line system allows for many fish to detect gentle currents and vibrations, Portsmouth Tropical Fish as well as to sense the motion of other nearby fish and prey. [15] In 2003, Portsmouth Tropical Fish it was concluded by Scottish scientists at Edinburgh University performing research on rainbow trout that fish exhibit behaviors often associated with pain[16]. Professor James D. Rose of the University of Wyoming published a critique of the study.[17] Rose had already published his own study a year earlier concluding that fish cannot feel pain as they lack the appropriate neocortex of the brain[18]. Fish such as catfish and sharks, Portsmouth Tropical Fish have organs that detect low levels electric current. Other fish, Portsmouth Tropical Fish like the electric eel, Portsmouth Tropical Fish can produce their own electricity.

 

Muscular system

 

    Fish locomotion

 

Most fish move by contracting paired sets of muscles on either side of the backbone alternately. These contractions form S-shaped curves that move down the body of the fish. As each curve reaches the back fin, Portsmouth Tropical Fish backward force is created. This backward force, Portsmouth Tropical Fish in conjunction with the fins, Portsmouth Tropical Fish moves the fish forward. The fish's fins are used like an airplane's stabilizers. Fins also increase the surface area of the tail, Portsmouth Tropical Fish allowing for an extra boost in speed. The streamlined body of the fish decreases the amount of friction as they move through water. Since body tissue is more dense than water, Portsmouth Tropical Fish fish must compensate for the difference or they will sink. Many bony fishes have an internal organ called a swim bladder that adjust their buoyancy through manipulation of gases.

 

Reproductive system

 

    Further information: Spawning

 

Organs

 

Fish reproductive organs include testes and ovaries. In most fish species, Portsmouth Tropical Fish gonads are paired organs of similar size, Portsmouth Tropical Fish which can be partially or totally fused.[19] There may also be a range of secondary reproductive organs that help in increasing a fish's fitness.

 

In terms of spermatogonia distribution, Portsmouth Tropical Fish the structure of teleosts testes has two types: in the most common, Portsmouth Tropical Fish spermatogonia occur all along the seminiferous tubules, Portsmouth Tropical Fish while in Atherinomorph fishes they are confined to the distal portion of these structures. Fishes can present cystic or semi-cystic spermatogenesis in relation to the phase of release of germ cells in cysts to the seminiferous tubules lumen.[19]

 

Fish ovaries may be of two types: gymnovarian or cystovarian. In the first type, Portsmouth Tropical Fish the oocytes are released directly into the coelomic cavity and then eliminated. In the second type, Portsmouth Tropical Fish the oocytes are conveyed to the exterior through the oviduct.[20] Gymnovaries are the primitive condition found in lungfishes, Portsmouth Tropical Fish sturgeons, Portsmouth Tropical Fish and bowfins. Cystovaries are the condition that characterizes most of the teleosts, Portsmouth Tropical Fish where the ovary lumen has continuity with the oviduct.[19]

 

Oogonia development in teleosts fish varies according to the group, Portsmouth Tropical Fish and the determination of oogenesis dynamics allows the understanding of maturation and fertilization processes. Changes in the nucleus, Portsmouth Tropical Fish ooplasm, Portsmouth Tropical Fish and the surrounding layers characterize the oocyte maturation process.[19]

 

Postovulatory follicles are structures formed after oocyte release; they do not have endocrine function, Portsmouth Tropical Fish present a wide irregular lumen, Portsmouth Tropical Fish and are rapidly reabosrbed in a process involving the apoptosis of follicular cells. A degenerative process called follicular atresia reabsorbs vitellogenic oocytes not spawned. This process can also occur, Portsmouth Tropical Fish but less frequently, Portsmouth Tropical Fish in oocytes in other development stages.[19]

 

Some fish are hermaphrodites, Portsmouth Tropical Fish either having testes and ovaries at different phases in the life cycle. However, Portsmouth Tropical Fish there are even some fish, Portsmouth Tropical Fish such as hamlets, Portsmouth Tropical Fish that are simultaneously male and female.

 

Reproductive method

 

Over 97% of all known fishes are oviparous, Portsmouth Tropical Fish [21] that is, Portsmouth Tropical Fish the eggs develop outside the mother's body. Examples of oviparous fishes include salmon, Portsmouth Tropical Fish goldfish, Portsmouth Tropical Fish cichlids, Portsmouth Tropical Fish tuna, Portsmouth Tropical Fish and eels. In the majority of these species, Portsmouth Tropical Fish fertilisation takes place outside the mother's body, Portsmouth Tropical Fish with the male and female fish shedding their gametes into the surrounding water. However, Portsmouth Tropical Fish a few oviparous fishes practise internal fertilisation, Portsmouth Tropical Fish with the male using some sort of intromittent organ to deliver sperm into the genital opening of the female, Portsmouth Tropical Fish most notably the oviparous sharks, Portsmouth Tropical Fish such as the horn shark, Portsmouth Tropical Fish and oviparous rays, Portsmouth Tropical Fish such as skates. In these cases, Portsmouth Tropical Fish the male is equipped with a pair of modified pelvic fins known as claspers.

 

The newly-hatched young of oviparous fish are called larvae. They are usually poorly formed, Portsmouth Tropical Fish carry a large yolk sac (from which they gain their nutrition) and are very different in appearance to juvenile and adult specimens of their species. The larval period in oviparous fish is relatively short however (usually only several weeks), Portsmouth Tropical Fish and larvae rapidly grow and change appearance and structure (a process termed metamorphosis) to resemble juveniles of their species. During this transition larvae use up their yolk sac and must switch from yolk sac nutrition to feeding on zooplankton prey, Portsmouth Tropical Fish a process which is dependent on zooplankton prey densities and causes many mortalities in larvae.

 

Ovoviviparous fish are ones in which the eggs develop inside the mother's body after internal fertilization but receive little or no nutrition from the mother, Portsmouth Tropical Fish depending instead on the yolk. Each embryo develops in its own egg. Familiar examples of ovoviviparous fishes include guppies, Portsmouth Tropical Fish angel sharks, Portsmouth Tropical Fish and coelacanths.

 

Some species of fish are viviparous. In such species the mother retains the eggs, Portsmouth Tropical Fish as in ovoviviparous fishes, Portsmouth Tropical Fish but the embryos receive nutrition from the mother in a variety of different ways. Typically, Portsmouth Tropical Fish viviparous fishes have a structure analogous to the placenta seen in mammals connecting the mother's blood supply with the that of the embryo. Examples of viviparous fishes of this type include the surf-perches, Portsmouth Tropical Fish splitfins, Portsmouth Tropical Fish and lemon shark. The embryos of some viviparous fishes exhibit a behaviour known as oophagy where the developing embryos eat eggs produced by the mother. This has been observed primarily among sharks, Portsmouth Tropical Fish such as the shortfin mako and porbeagle, Portsmouth Tropical Fish but is known for a few bony fish as well, Portsmouth Tropical Fish such as the halfbeak Nomorhamphus ebrardtii.[22] Intrauterine cannibalism is an even more unusual mode of vivipary, Portsmouth Tropical Fish where the largest embryos in the uterus will eat their weaker and smaller siblings. This behaviour is also most commonly found among sharks, Portsmouth Tropical Fish such as the grey nurse shark, Portsmouth Tropical Fish but has also been reported for Nomorhamphus ebrardtii.[22]

 

Aquarists commonly refer to ovoviviparous and viviparous fishes as livebearers.

 

Immune system

 

Types of immune organs vary between different types of fish.[23] In the jawless fish (lampreys and hagfishes), Portsmouth Tropical Fish true lymphoid organs are absent. Instead, Portsmouth Tropical Fish these fish rely on regions of lymphoid tissue within other organs to produce their immune cells. For example, Portsmouth Tropical Fish erythrocytes, Portsmouth Tropical Fish macrophages and plasma cells are produced in the anterior kidney (or pronephros) and some areas of the gut (where granulocytes mature) resemble primitive bone marrow in hagfish. Cartilaginous fish (sharks and rays) have a more advanced immune system than the jawless fish. They have three specialized organs that are unique to chondrichthyes; the epigonal organs (lymphoid tissue similar to bone marrow of mammals) that surround the gonads, Portsmouth Tropical Fish the Leydig’s organ within the walls of their esophagus, Portsmouth Tropical Fish and a spiral valve in their intestine. All these organs house typical immune cells (granulocytes, Portsmouth Tropical Fish lymphocytes and plasma cells). They also possess an identifiable thymus and a well-developed spleen (their most important immune organ) where various lymphocytes, Portsmouth Tropical Fish plasma cells and macrophages develop and are stored. Chondrostean fish (sturgeons, Portsmouth Tropical Fish paddlefish and birchirs) possess a major site for the production of granulocytes within a mass that is associated with the meninges (membranes surrounding the central nervous system) and their heart is frequently covered with tissue that contains lymphocytes, Portsmouth Tropical Fish reticular cells and a small number of macrophages. The chondrostean kidney is an important hemopoietic organ; where erythrocytes, Portsmouth Tropical Fish granulocytes, Portsmouth Tropical Fish lymphocytes and macrophages develop. Like chondrostean fish, Portsmouth Tropical Fish the major immune tissues of bony fish (or teleostei) include the kidney (especially the anterior kidney), Portsmouth Tropical Fish where many different immune cells are housed.[24] In addition, Portsmouth Tropical Fish teleost fish possess a thymus, Portsmouth Tropical Fish spleen and scattered immune areas within mucosal tissues (e.g. in the skin, Portsmouth Tropical Fish gills, Portsmouth Tropical Fish gut and gonads). Much like the mammalian immune system, Portsmouth Tropical Fish teleost erythrocytes, Portsmouth Tropical Fish neutrophils and granulocytes are believed to reside in the spleen whereas lymphocytes are the major cell type found in the thymus.[25][26] Recently, Portsmouth Tropical Fish a lymphatic system similar to that described in mammals was described in one species of teleost fish, Portsmouth Tropical Fish the zebrafish. Although not confirmed as yet, Portsmouth Tropical Fish this system presumably will be where naive (unstimulated) T cells will accumulate while waiting to encounter an antigen.[27]

 

Evolution

 

The early fossil record on fish is not very clear. It appears it was not a successful enough animal early in its evolution to leave many fossils. However, Portsmouth Tropical Fish this would eventually change over time as it became a dominant form of sea life and eventually branching to include land vertebrates such as amphibians, Portsmouth Tropical Fish reptiles, Portsmouth Tropical Fish and mammals.

 

The formation of the hinged jaw appears to be what resulted in the later proliferation of fish because un-jawed fish left very few ancestors.[28] Lampreys may be a rough representative of pre-jawed fish. The first jaws are found in Placodermi fossils. It is unclear if the advantage of a hinged jaw is greater biting force, Portsmouth Tropical Fish respiratory-related, Portsmouth Tropical Fish or a combination.

 

Some speculate that fish may have evolved from a creature similar to a coral-like Sea squirt, Portsmouth Tropical Fish whose larvae resemble primitive fish in some key ways. The first ancestors of fish may have kept the larval form into adulthood (as some sea squirts do today, Portsmouth Tropical Fish see Neoteny), Portsmouth Tropical Fish although the reversal of this case is also possible. Candidates for early fish include Agnatha such as Haikouichthys, Portsmouth Tropical Fish Myllokunmingia, Portsmouth Tropical Fish Pikaia, Portsmouth Tropical Fish and Conodonts.

 

Homeothermy

A 3 to 4 m great white shark off Isla Guadalupe

A 3 to 4 m great white shark off Isla Guadalupe

 

Although most fish are exclusively aquatic and cold-blooded, Portsmouth Tropical Fish there are exceptions to both cases. Fish from a number of different groups have evolved the capacity to live out of the water for extended periods of time. Of these amphibious fish some such as the mudskipper can live and move about on land for up to several days. Also, Portsmouth Tropical Fish certain species of fish maintain elevated body temperatures to varying degrees. Endothermic teleosts (bony fishes) are all in the suborder Scombroidei and include the billfishes, Portsmouth Tropical Fish tunas, Portsmouth Tropical Fish and one species of "primitive" mackerel (Gasterochisma melampus). All sharks in the family Lamnidae – shortfin mako, Portsmouth Tropical Fish long fin mako, Portsmouth Tropical Fish white, Portsmouth Tropical Fish porbeagle, Portsmouth Tropical Fish and salmon shark – are known to have the capacity for endothermy, Portsmouth Tropical Fish and evidence suggests the trait exists in family Alopiidae (thresher sharks). The degree of endothermy varies from the billfish, Portsmouth Tropical Fish which warm only their eyes and brain, Portsmouth Tropical Fish to bluefin tuna and porbeagle sharks who maintain body temperatures elevated in excess of 20 °C above ambient water temperatures. See also gigantothermy. Endothermy, Portsmouth Tropical Fish though metabolically costly, Portsmouth Tropical Fish is thought to provide advantages such as increased contractile force of muscles, Portsmouth Tropical Fish higher rates of central nervous system processing, Portsmouth Tropical Fish and higher rates of digestion.

 

Diseases

 

Like other animals, Portsmouth Tropical Fish fish can suffer from a wide variety of diseases and parasites. To prevent disease they have a variety of non-specific defences and specific defences. Non-specific defences include the skin and scales, Portsmouth Tropical Fish as well as the mucus layer secreted by the epidermis that traps microorganisms and inhibits their growth. Should pathogens breach these defences, Portsmouth Tropical Fish fish can develop an inflammatory response that increases the flow of blood to the infected region and delivers the white blood cells that will attempt to destroy the pathogens. Specific defences are specialised responses to particular pathogens recognised by the fish's body, Portsmouth Tropical Fish in other words, Portsmouth Tropical Fish an immune response.[29] In recent years, Portsmouth Tropical Fish vaccines have become widely used in aquaculture and also with ornamental fish, Portsmouth Tropical Fish for example the vaccines for furunculosis in farmed salmon and koi herpes virus in koi.

 

Some fish will also take advantage of cleaner fish for removal of external parasites. The best known of these are the cleaner wrasses of the genus Labroides found on coral reefs in the Indian Ocean and Pacific Ocean. These small fish maintain so-called "cleaning stations" where other fish, Portsmouth Tropical Fish known as hosts, Portsmouth Tropical Fish will congregate and perform specific movements to attract the attention of the cleaner fish.Cleaning behaviours have been observed in a number of other fish groups, Portsmouth Tropical Fish including an interesting case between two cichlids of the same genus, Portsmouth Tropical Fish Etroplus maculatus, Portsmouth Tropical Fish the cleaner fish, Portsmouth Tropical Fish and the much larger Etroplus suratensis, Portsmouth Tropical Fish the host.

 

Importance to humans

 

Economic importance

 

    Aquaculture

    Fish (food)

    Fishing

    Fish farming

 

Recreation

 

    Angling

    Fishkeeping

    Sport fishing

 

Conservation

A Whale shark, Portsmouth Tropical Fish the world's largest fish, Portsmouth Tropical Fish is classified as Vulnerable.

A Whale shark, Portsmouth Tropical Fish the world's largest fish, Portsmouth Tropical Fish is classified as Vulnerable.

 

As of 2006, Portsmouth Tropical Fish the IUCN Red List describes 1,173 species of fish as being threatened with extinction.[34] Included on this list are species such as Atlantic cod, Portsmouth Tropical Fish [35] Devil's Hole pupfish, Portsmouth Tropical Fish [36] coelacanths, Portsmouth Tropical Fish [37] and great white sharks.[38] Because fish live underwater they are much more difficult to study than terrestrial animals and plants, Portsmouth Tropical Fish and information about fish populations is often lacking. However, Portsmouth Tropical Fish freshwater fish seem particularly threatened because they often live in relatively small areas. For example, Portsmouth Tropical Fish the Devil's Hole pupfish occupies only a single 3 m by 6 m pool.[39]

 

Overfishing

 

In the case of edible fishes such as cod and tuna a major threat is overfishing.[40][41] Where overfishing persists, Portsmouth Tropical Fish it eventually causes the collapse of the fish population (known as a "stock") because the population can't breed fast enough to replace the individuals removed by fishing. One well-studied example of the collapse of a fishery is the Pacific sardine Sadinops sagax caerulues fishery off the coast of California. From a peak in 1937 of 790,000 tonnes the amount of fish landed steadily declined to a mere 24,000 tonnes in 1968, Portsmouth Tropical Fish at which point the fishery stopped as no longer economically viable. Such commercial extinction does not mean that the fish itself goes extinct, Portsmouth Tropical Fish merely that it can no longer sustain a profitable fishery.[42] The main tension between fisheries science and the fishing industry is the need to balance conservation with preserving the livelihoods of fishermen. In places such as Scotland, Portsmouth Tropical Fish Newfoundland, Portsmouth Tropical Fish and Alaska the fishing industry is a major employer, Portsmouth Tropical Fish so governments have a vested interest in finding a balance between conserving fish stocks while maintaining an economic level of commercial fishing.[43][44] On the other hand, Portsmouth Tropical Fish scientists and conservations push for increasingly stringent protection for fish stocks, Portsmouth Tropical Fish warning that many stocks could be wiped out within fifty years.[45][46]

 

Habitat destruction

 

A key stress on both freshwater and marine ecosystems is habitat degradation including water pollution, Portsmouth Tropical Fish the building of dams, Portsmouth Tropical Fish removal of water for use by humans, Portsmouth Tropical Fish and the introduction of exotic species.[47] An example of a fish that has become endangered because of habitat change is the pallid sturgeon, Portsmouth Tropical Fish a North American freshwater fish that living in rivers that have all been changed by human activity in a variety of different ways.[48]

 

Exotic species

 

Introduction of exotic species has occurred in a variety of places and for many different reasons. One of the nest studied (and most severe) examples was the introduction of Nile perch into Lake Victoria. Since the 1960s the Nile perch gradually exterminated the 500 species of cichlid fishes found only in this lake and nowhere else. Some species survive now only in captive breeding programmes, Portsmouth Tropical Fish but others are probably extinct.[49] Carp, Portsmouth Tropical Fish snakeheads, Portsmouth Tropical Fish [50] tilapia, Portsmouth Tropical Fish European perch, Portsmouth Tropical Fish brown trout, Portsmouth Tropical Fish rainbow trout, Portsmouth Tropical Fish and sea lampreys are other examples of fish that have caused problems by being introduced into alien environments.

 

Aquarium collecting

 

    Fishkeeping#Conservation_and_Science

 

Culture

 

Through the ages, Portsmouth Tropical Fish many cultures have featured fish in their legends and myths, Portsmouth Tropical Fish from the "great fish" that swallowed Jonah the Prophet through to the half-human, Portsmouth Tropical Fish half-fish mermaid around which books and movies have been centred (e.g., Portsmouth Tropical Fish Splash). Among the deities said to take the form of a fish are Ika-Roa of the Polynesians, Portsmouth Tropical Fish Dagon of various ancient Semitic peoples, Portsmouth Tropical Fish and Matsya of the Dravidas of India. The astrological symbol Pisces is based on a constellation of the same name, Portsmouth Tropical Fish but there is also a second fish constellation in the night sky, Portsmouth Tropical Fish Piscis Austrinus. Fish have been used figuratively in many different ways, Portsmouth Tropical Fish for example the ichthys used by early Christians to identify themselves through to the fish as a symbol of fertility among Bengalis.[51] Fish have also featured prominently in art and literature, Portsmouth Tropical Fish as in movies such as Finding Nemo and books such as The Old Man and the Sea. Large fish, Portsmouth Tropical Fish particularly sharks, Portsmouth Tropical Fish have frequently been the subject of horror movies and thrillers, Portsmouth Tropical Fish most notably the novel Jaws, Portsmouth Tropical Fish which spawned a series of films of the same name that in turn inspired similar films or parodies such as Shark Tale, Portsmouth Tropical Fish Snakehead Terror, Portsmouth Tropical Fish and Piranha.

 

Plural forms

These squirrelfish are shoaling, Portsmouth Tropical Fish not schooling: though swimming as a group, Portsmouth Tropical Fish their speed and direction is not synchronised.

These squirrelfish are shoaling, Portsmouth Tropical Fish not schooling: though swimming as a group, Portsmouth Tropical Fish their speed and direction is not synchronised.

These jacks are schooling because their swimming is synchronised.

These jacks are schooling because their swimming is synchronised.

 

Though often used interchangeably, Portsmouth Tropical Fish these pairs of words actually mean different things. Fish is used either as singular noun or to describe a group of specimens from a single species. Fishes describes a group containing more than one species.[52] Hence, Portsmouth Tropical Fish as plurals, Portsmouth Tropical Fish these words could be used thus:

 

    * My aquarium contains three different fishes: guppies, Portsmouth Tropical Fish platies, Portsmouth Tropical Fish and swordtails.

    * The North Atlantic stock of Gadus morhua is estimated to contain several million fish.

 

A random assemblage of fishes merely using some localised resource such as food or nesting sites is known simply as an aggregation. When fish come together in an interactive, Portsmouth Tropical Fish social grouping, Portsmouth Tropical Fish then they may be forming either a shoal or a school depending on the degree of organisation. A shoal is a loosely organised group where each fish swims and forages independently but is attracted to other members of the group and adjusts its behaviour, Portsmouth Tropical Fish such as swimming speed, Portsmouth Tropical Fish so that it remains close to the other members of the group. Schools of fish are much more tightly organised, Portsmouth Tropical Fish synchronising their swimming so that all fish move at the same speed and in the same direction. Shoaling and schooling behaviour is believed to provide a variety of advantages (see article on swarming, Portsmouth Tropical Fish the term used to cover such behaviours in animals).[53]

 

    * Cichlids congregating at lekking sites form an aggregation.

    * Many minnows and characins form shoals.

    * Classic examples of schooling fish are anchovies, Portsmouth Tropical Fish herrings, Portsmouth Tropical Fish and silversides.

 

It should be noted that while school and shoal have different meanings within biology, Portsmouth Tropical Fish they are often treated as synonyms by non-specialists, Portsmouth Tropical Fish with speakers of British English using "shoal" to describe any grouping of fish, Portsmouth Tropical Fish while speakers of American English often using "school" just as loosely.

 

An aquarium (plural aquariums or aquaria) is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Aquaria are primarily used for fishkeeping, Portsmouth Tropical Fish although invertebrates, Portsmouth Tropical Fish amphibians, Portsmouth Tropical Fish marine mammals, Portsmouth Tropical Fish and aquatic plants are also housed in aquaria. The term combines the Latin root aqua, Portsmouth Tropical Fish meaning water, Portsmouth Tropical Fish with the suffix -arium, Portsmouth Tropical Fish meaning "a place for relating to".[1]

 

The aquarium has a long history and maintaining an aquarium has become immensely popular worldwide; a person who owns or maintains an aquarium is known as an aquarist. Aquaria can come in a variety of materials, Portsmouth Tropical Fish shapes, Portsmouth Tropical Fish and sizes. They are typically constructed of glass or high-strength plastic. Cuboid aquaria are also known as fish tanks or simply tanks, Portsmouth Tropical Fish while bowl-shaped aquaria are also known as fish bowls. Size can range from a small glass bowl to immense public aquaria. A number of components are used to maintain appropriate water quality and characteristics suitable for the aquarium's residents. There are many types of aquaria, Portsmouth Tropical Fish classified by the organisms maintained or the type of environment that is mimicked.

Contents

[hide]

 

    * 1 History and popularization

    * 2 Design

          o 2.1 Materials

          o 2.2 Styles

          o 2.3 Aquarium size and volume

    * 3 Components

    * 4 Aquarium classifications

    * 5 Public aquaria

    * 6 See also

    * 7 References

    * 8 External links

 

History and popularization

 

Fishkeeping in artificial environments has existed for centuries. In the Roman Empire, Portsmouth Tropical Fish the first fish to be brought indoors was the sea barbel, Portsmouth Tropical Fish which was kept under guest beds in small tanks made of marble. With the introduction of glass panes around the year 50, Portsmouth Tropical Fish the Romans replaced one wall of the marble tank, Portsmouth Tropical Fish improving their view of the fish. In 1369, Portsmouth Tropical Fish the Chinese Emperor, Portsmouth Tropical Fish Hongwu, Portsmouth Tropical Fish established a porcelain company that produced large porcelain tubs for maintaining goldfish; over time, Portsmouth Tropical Fish these tubs were produced more and more like modern fish bowls.Leonhard Baldner, Portsmouth Tropical Fish who wrote Vogel-, Portsmouth Tropical Fish Fisch- und Tierbuch (Bird, Portsmouth Tropical Fish Fish, Portsmouth Tropical Fish and Animal Book) in 1666, Portsmouth Tropical Fish maintained weather loaches and newts.[3]

 

In 1836, Portsmouth Tropical Fish soon after his invention of the Wardian case, Portsmouth Tropical Fish Ward proposed to use his tanks for tropical animals, Portsmouth Tropical Fish and in 1841 he did so, Portsmouth Tropical Fish though only with aquatic plants and toy fish. However, Portsmouth Tropical Fish real animals were soon housed. In 1838, Portsmouth Tropical Fish Félix Dujardin noted owning a saltwater aquarium, Portsmouth Tropical Fish though he did not use the term.[4] In 1846, Portsmouth Tropical Fish Anna Thynne maintained stony corals and seaweed for almost three years, Portsmouth Tropical Fish and was credited as the creator of the first balanced marine aquarium in London.[5] At about the same time, Portsmouth Tropical Fish Robert Warington experimented with a 13-gallon container, Portsmouth Tropical Fish which contained goldfish, Portsmouth Tropical Fish eelgrass, Portsmouth Tropical Fish and snails, Portsmouth Tropical Fish creating one of the first stable aquaria; he published his findings in 1850 in the Chemical Society's journal.[6]

Pike in an aquarium c. 1908, Portsmouth Tropical Fish at the Detroit Aquarium, Portsmouth Tropical Fish Belle Isle Park.

Pike in an aquarium c. 1908, Portsmouth Tropical Fish at the Detroit Aquarium, Portsmouth Tropical Fish Belle Isle Park.

 

The keeping of fish in an aquarium became a popular hobby and spread quickly. In the United Kingdom, Portsmouth Tropical Fish it became popular after ornate aquaria in cast iron frames were featured at the Great Exhibition of 1851. In 1853, Portsmouth Tropical Fish the first large public aquarium opened in the London Zoo and came to be known as the Fish House.[7] Philip Henry Gosse was the first person to actually use the word "aquarium", Portsmouth Tropical Fish opting for this term (instead of "vivarium") in 1854 in his book The Aquarium: An Unveiling of the Wonders of the Deep Sea. In this book, Portsmouth Tropical Fish Gosse primarily discussed saltwater aquaria.[8] In the 1850s, Portsmouth Tropical Fish the aquarium became a fad in the United Kingdom.[9]

 

Germans soon rivaled the British in their interest. In 1854, Portsmouth Tropical Fish two articles about the saltwater aquaria of the United Kingdom were published in Die Gartenlaube (The Garden House) entitled Der Ocean auf dem Tische (The Ocean on the Table) by an anonymous author. However, Portsmouth Tropical Fish in 1856, Portsmouth Tropical Fish Der See im Glase (The Lake in a Glass) was published, Portsmouth Tropical Fish discussing freshwater aquaria, Portsmouth Tropical Fish which were much easier to maintain in landlocked areas.[10] During the 1870s, Portsmouth Tropical Fish some of the first aquarist societies were appearing in Germany.[11] The United States soon followed. Published in 1858, Portsmouth Tropical Fish Henry D. Butler's The Family Aquarium was one of the first books written in the United States solely about the aquarium.[12] According to the July issue of The North American Review of the same year, Portsmouth Tropical Fish William Stimson may have owned some of the first functional aquaria, Portsmouth Tropical Fish and had as many as seven or eight.[13] The first aquarist society in the United States was founded in New York City in 1893, Portsmouth Tropical Fish followed by others.[11] The New York Aquarium Journal, Portsmouth Tropical Fish first published in October 1876, Portsmouth Tropical Fish is considered to be the world's first aquarium magazine.[14]

 

In the Victorian era in the United Kingdom, Portsmouth Tropical Fish a common design for the home aquarium was a glass front with the other sides made of wood (made watertight with a pitch coating). The bottom would be made of slate and heated from below.[15] More advanced systems soon began to be introduced, Portsmouth Tropical Fish along with tanks of glass in metal frames.[15] During the latter half of the 19th century, Portsmouth Tropical Fish a variety of aquarium designs were explored, Portsmouth Tropical Fish such as hanging the aquarium on a wall, Portsmouth Tropical Fish mounting it as part of a window, Portsmouth Tropical Fish or even combining it with a birdcage.[16]

 

Aquaria became more widely popular as houses became almost universally electrified after World War I. With electricity great improvements were made in aquarium technology, Portsmouth Tropical Fish allowing artificial lighting as well as aeration, Portsmouth Tropical Fish filtration, Portsmouth Tropical Fish and heating of the water.[17] Initially, Portsmouth Tropical Fish amateur aquarists kept native fish (with the exception of goldfish); the entrance of exotic species from overseas also allowed aquaria to become even more popular.[18] Jugs made from a variety of materials were initially used to import fish from overseas, Portsmouth Tropical Fish including innovations such as using a bicycle foot pump for aeration.[19] Plastic shipping bags were introduced in the 1950s, Portsmouth Tropical Fish making it easier to ship fish.[20] The eventual availability of air freight, Portsmouth Tropical Fish which allowed a much wider variety of fish, Portsmouth Tropical Fish especially marine, Portsmouth Tropical Fish to be successfully imported from distant regions of origin, Portsmouth Tropical Fish consequently attracted new hobbyists.[21] In the 1960s, Portsmouth Tropical Fish a great breakthrough was reached. Metal frames made marine aquaria almost impossible due to corrosion, Portsmouth Tropical Fish but the development of silicone sealant allowed the first all-glass aquaria. The frames remained, Portsmouth Tropical Fish however, Portsmouth Tropical Fish though purely for aesthetic reasons.[15]

 

Aquarium keeping is now a popular hobby around the world, Portsmouth Tropical Fish with about 60 million aquarists worldwide.[citation needed] In the United States, Portsmouth Tropical Fish aquarium keeping is the second-most popular hobby after stamp collecting.[22] The number of fish kept in aquaria vary by country. In 1999 it was estimated that over nine million U.S. households own an aquarium.[23] In 2005, Portsmouth Tropical Fish it was estimated that 139 million freshwater fish and 9 million saltwater fish were kept in aquaria in the U.S.[24] Similarly, Portsmouth Tropical Fish estimates of the numbers of fish kept in aquaria in Germany number at least 36 million.[22] The hobby has the strongest following in Europe, Portsmouth Tropical Fish Asia, Portsmouth Tropical Fish and North America. In the United States, Portsmouth Tropical Fish 40 percent of aquarists maintain two or more tanks at any one time.[citation needed]

 

Design

An 80 litre home aquarium.

An 80 litre home aquarium.

 

Materials

 

Most aquaria consist of simple glass panes bonded together by silicone. Usually plastic frames are attached to the upper and lower edges for decoration. Price, Portsmouth Tropical Fish availability, Portsmouth Tropical Fish and reliability make the glass aquarium an industry standard for sizes up to about 1000 litres (250 gal). However, Portsmouth Tropical Fish glass is brittle and has very little give before fracturing, Portsmouth Tropical Fish though generally the sealant fails first.[25] Aquaria come in a variety of shapes such as cuboid, Portsmouth Tropical Fish hexagonal, Portsmouth Tropical Fish angled to fit in a corner (L-shaped), Portsmouth Tropical Fish bow-front (the front side curves outwards), Portsmouth Tropical Fish and more.[26] Fish bowls are generally either plastic or glass, Portsmouth Tropical Fish either spherical or some other round configuration.

 

Acrylic aquaria are also available and are the primary competitor with glass. Acrylics are stronger than glass, Portsmouth Tropical Fish and much lighter. Acrylic-soluble cements are used to directly fuse acrylic together (as opposed to simply sealing the seam).[25] Acrylic allows for the formation of unusual shapes, Portsmouth Tropical Fish such as hexagonal.[15] Compared to glass, Portsmouth Tropical Fish acrylics are easy to scratch; care must be taken with organisms with shells and teeth.[25]

 

Laminated glass might be used, Portsmouth Tropical Fish which combines the advantages of both glass and acrylic.[25]

 

Large aquaria might use stronger materials such as fiberglass-reinforced plastics. However, Portsmouth Tropical Fish this material is not transparent.[25] Reinforced concrete is used for aquaria where weight and space are not factors. Concrete must be coated with a waterproof layer to prevent the water from breaking down the concrete as well as prevent contamination from the concrete.[25]

 

Styles

 

Aquaria can come in more creative flavors. Aquariums have been fashioned into coffee tables, Portsmouth Tropical Fish sinks, Portsmouth Tropical Fish and even toilets. Another such example is the Macquarium, Portsmouth Tropical Fish an aquarium made from the shell of an Apple Macintosh computer.[27]

 

A kreisel tank is a circular aquarium designed to hold delicate animals such as jellyfish. These aquariums provide slow, Portsmouth Tropical Fish circular water flow with a lack of physical objects.[28] Originally a German design (kreisel means spinning top), Portsmouth Tropical Fish the tank is designed to have no sharp corners, Portsmouth Tropical Fish and keeps the housed animals away from the plumbing. Water moving into the tank gives a gentle flow that keeps the inhabitants suspended, Portsmouth Tropical Fish and water leaving the tank is covered by a delicate screen that prevents the inhabitants from getting stuck. There are several types of kreisel tanks. In a true kreisel, Portsmouth Tropical Fish a perfectly circular tank has a circular, Portsmouth Tropical Fish submerged, Portsmouth Tropical Fish lid. Pseudokreisels, Portsmouth Tropical Fish have a curved bottom surface and a top surface flat, Portsmouth Tropical Fish similar to the shape of either a "U" or a semicircle.[29] It is possible to combine these designs; a circular shaped tank is used without a lid or cover, Portsmouth Tropical Fish and the surface of the water acts as the continuation of circular flow.

 

Aquarium size and volume

A large aquarium at the Osaka Aquarium houses a whale shark.

A large aquarium at the Osaka Aquarium houses a whale shark.

 

An aquarium can range from a small glass bowl containing less than a litre (34 fl.oz.) of water to immense public aquaria which can house entire ecosystems such as kelp forests. Larger aquaria are typically recommended to hobbyists due to their resistance to rapid fluctuations of temperature and pH, Portsmouth Tropical Fish allowing for greater system stability.[26]

 

Aquaria kept in homes by hobbyists can be as small as 11 litres (3 gal); this size is widely considered the smallest practical system with filtration and other basic systems. On the other hand, Portsmouth Tropical Fish reef aquaria under 100 litres (20 gal) earn a special place in the aquarium hobby; these aquaria, Portsmouth Tropical Fish termed nano reefs, Portsmouth Tropical Fish are known to be more difficult due to their small water volume. Practical limitations, Portsmouth Tropical Fish most notably the weight (One litre of fresh water weighs 1 kilogram (8.3 lb gal-1), Portsmouth Tropical Fish and salt water is even denser) and internal water pressure (requiring thick, Portsmouth Tropical Fish strong glass siding) of a large aquarium, Portsmouth Tropical Fish keep most home aquaria to a maximum of around 1 cubic metre in volume (1000 kg or 2200 lb). Indeed, Portsmouth Tropical Fish larger aquariums can even threaten the floor beneath the aquarium.[26] Some dedicated aquarists, Portsmouth Tropical Fish however, Portsmouth Tropical Fish have been known to construct custom aquaria of up to many thousands of litres, Portsmouth Tropical Fish at great effort and expense.[30][31]

 

Aquaria within public aquariums designed for exhibition of large species or environments can be dramatically larger than any home aquarium. The Shedd Aquarium in Chicago, Portsmouth Tropical Fish for example, Portsmouth Tropical Fish features an individual aquarium of 7.7 million litres (2 million gallons).

 

Components

Filtration system in a typical aquarium: (1) Intake. (2) Mechanical filtration. (3) Chemical filtration. (4) Biological filtration medium. (5) Outflow to tank.

Filtration system in a typical aquarium: (1) Intake. (2) Mechanical filtration. (3) Chemical filtration. (4) Biological filtration medium. (5) Outflow to tank.

 

The typical hobbyist aquarium includes a filtration system, Portsmouth Tropical Fish an artificial lighting system, Portsmouth Tropical Fish and a heater or chiller depending on the inhabitants of the aquarium. Many aquaria incorporate a hood, Portsmouth Tropical Fish which prevents evaporation and protects fish from leaving the aquarium (or anything else from entering the aquarium). They also often hold lights.[26] Hoods can be opened and closed easily for access into the aquarium.

 

Combined biological and mechanical aquarium filtration systems are commonly used; these are designed to either convert ammonia to nitrate or remove it or sometimes remove phosphate from water, Portsmouth Tropical Fish removing them being at the expense of aquatic plants. Particulates incorporated into the filter can provide energy for microbes and sponges that do these things. Filtration systems are often the most complex component of home aquaria, Portsmouth Tropical Fish and various designs and combinations are used.[32]

 

Aquarium heaters combine a heating element with a thermostat, Portsmouth Tropical Fish allowing an aquarist to regulate water temperature at a level above that of the surrounding air, Portsmouth Tropical Fish whereas coolers and chillers (refrigeration devices) are for use in cold water aquaria, Portsmouth Tropical Fish or anywhere the ambient room temperature is above the desired tank temperature.[26] A variety of different thermometers are used, Portsmouth Tropical Fish such as the glass alcohol thermometers, Portsmouth Tropical Fish adhesive external plastic strip thermometers, Portsmouth Tropical Fish and even battery-powered LCD thermometers.[26] In addition, Portsmouth Tropical Fish some aquarists use air pumps attached to airstones or water pumps to increase water circulation and supply adequate gas exchange at the water surface. Wave-making devices have also been constructed to provide wave action.[25]

 

An aquarium's physical characteristics form another aspect of aquarium design. Size, Portsmouth Tropical Fish lighting conditions, Portsmouth Tropical Fish density of floating and rooted plants, Portsmouth Tropical Fish placement of bogwood, Portsmouth Tropical Fish creation of caves or overhangs, Portsmouth Tropical Fish type of substrate, Portsmouth Tropical Fish and other factors (including an aquarium's positioning within a room) can all affect the behavior and survival of tank inhabitants. The combined function of these elements is to maintain appropriate water quality and characteristics suitable for the aquarium's residents.

 

An aquarium is often also placed on a specially-made aquarium stand. Because of the weight of an aquarium, Portsmouth Tropical Fish they must be strong as well as level. A tank that is not level may distort, Portsmouth Tropical Fish leak, Portsmouth Tropical Fish or crack.[26] These are often built like cabinets to allow storage, Portsmouth Tropical Fish available in many styles so it can match room decor. Simple metal tank stands are also available.[26] Some sources say that polystyrene should be placed under the aquarium as a safety precaution.[26] However, Portsmouth Tropical Fish this may void certain warranties.[citation needed]

 

Aquarium classifications

A planted freshwater aquarium.

A planted freshwater aquarium.

 

From the outdoor ponds and glass jars of antiquity, Portsmouth Tropical Fish modern aquaria have evolved into a wide range of specialized systems. Individual aquaria can vary in size from a small bowl large enough for a single small fish, Portsmouth Tropical Fish to the huge public aquaria that can simulate entire marine ecosystems. A variety of different aquarium types exist; for the most part, Portsmouth Tropical Fish many of these classifications are based on the environment the aquarium intends to mimic.

 

One of the most basic ways to classify aquaria is their salinity. Freshwater aquaria are the most popular kind of aquarium due to their lower cost and ease of maintenance.Marine aquaria are generally more difficult to setup and maintain than freshwater aquaria. Along with fish species, Portsmouth Tropical Fish marine aquaria frequently feature a diverse range of invertebrates.[33]Brackish water aquaria combine elements of both marine and freshwater fishkeeping.Fish kept in brackish water aquaria generally come from habitats with varying salinity, Portsmouth Tropical Fish such as mangroves and estuaries. Certain subtypes of aquaria also exist within these types, Portsmouth Tropical Fish such as the reef aquarium, Portsmouth Tropical Fish a type of marine aquarium that houses coral.[33]

 

Another method to classify aquaria is their temperature range. Most aquarists maintain a tropical aquarium as these fish tend to be more colorful.However, Portsmouth Tropical Fish the coldwater aquarium is also popular, Portsmouth Tropical Fish which often includes fish such as goldfish.[33]

A saltwater aquarium.

A saltwater aquarium.

 

Aquaria may be grouped by their species selection. The community tank is the most common type of aquarium kept today, Portsmouth Tropical Fish where several non-aggressive species are housed peacefully together. Aggressive tanks, Portsmouth Tropical Fish in contrast, Portsmouth Tropical Fish house a limited number of species that can be aggressive toward other fish, Portsmouth Tropical Fish or are able to withstand aggression well. Species or specimen tanks usually only house one fish species, Portsmouth Tropical Fish along with plants, Portsmouth Tropical Fish perhaps found in the fishes' natural environment and decorations simulating a true ecosystem. This type is useful for fish that simply cannot be housed safely with other fish, Portsmouth Tropical Fish such as the electric eel, Portsmouth Tropical Fish as an extreme example. Some tanks of this sort are used simply to house adults for breeding. In these aquaria, Portsmouth Tropical Fish the aquarium fish, Portsmouth Tropical Fish invertebrates, Portsmouth Tropical Fish and plants may or may not originate from the same geographic region, Portsmouth Tropical Fish but generally tolerate similar water conditions.

 

Ecotype, Portsmouth Tropical Fish ecotope, Portsmouth Tropical Fish or biotope aquaria is another type based on species selection. In it, Portsmouth Tropical Fish an aquarist attempts to simulate a specific ecosystem found in the natural world, Portsmouth Tropical Fish bringing together fish, Portsmouth Tropical Fish invertebrate species, Portsmouth Tropical Fish and plants found only in that ecosystem in a tank with water conditions and decorations designed to simulate their natural environment. These ecotype aquaria might be considered the most sophisticated hobby aquaria; indeed, Portsmouth Tropical Fish reputable public aquaria all use this approach in their exhibits whenever possible. This approach best simulates the experience of observing an aquarium's inhabitants in the wild, Portsmouth Tropical Fish and also usually serves as the healthiest possible artificial environment for the tank's occupants.

 

Public aquaria

One of the large aquaria at the Georgia Aquarium, Portsmouth Tropical Fish USA.

One of the large aquaria at the Georgia Aquarium, Portsmouth Tropical Fish USA.

 

    Public aquarium

 

Public aquariums are facilities open to the public for viewing of aquatic species in aquaria. Most public aquariums feature a number of smaller aquaria, Portsmouth Tropical Fish as well those greater in size than could be kept by home aquarists. The largest tanks hold millions of U.S. gallons of water and can house large species, Portsmouth Tropical Fish including sharks or beluga whales. Dolphinariums are aquaria specifically for housing dolphins. Aquatic and semiaquatic animals, Portsmouth Tropical Fish including otters and penguins, Portsmouth Tropical Fish may also be kept by public aquariums. Public aquariums may also be included in larger establishments such as a marine mammal park or a marine park.