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, although invertebrates, amphibians, marine mammals, and aquatic plants are also housed in aquaria. The term combines the Latin root aqua, meaning water, with the suffix -arium, 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, shapes, and sizes. They are typically constructed of glass or high-strength plastic. Cuboid aquaria are also known as fish tanks or simply tanks, 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, classified by the organisms maintained or the type of environment that is mimicked.

History and popularization

Fishkeeping in artificial environments has existed for centuries. In the Roman Empire, the first fish to be brought indoors was the sea barbel, which was kept under guest beds in small tanks made of marble. With the introduction of glass panes around the year 50, the Romans replaced one wall of the marble tank, improving their view of the fish. In 1369, the Chinese Emperor, Hongwu, established a porcelain company that produced large porcelain tubs for maintaining goldfish; over time, these tubs were produced more and more like modern fish bowls.^[2] Leonhard Baldner, who wrote Vogel-, Fisch- und Tierbuch (Bird, Fish, and Animal Book) in 1666, maintained weather loaches and newts.^[3]

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

The keeping of fish in an aquarium became a popular hobby and spread quickly. In the United Kingdom, it became popular after ornate aquaria in cast iron frames were featured at the Great Exhibition of 1851. In 1853, 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", 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, Gosse primarily discussed saltwater aquaria.^[8] In the 1850s, the aquarium became a fad in the United Kingdom.^[9]

Germans soon rivaled the British in their interest. In 1854, 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, in 1856, Der See im Glase (The Lake in a Glass) was published, discussing freshwater aquaria, which were much easier to maintain in landlocked areas.^[10] During the 1870s, some of the first aquarist societies were appearing in Germany.^[11] The United States soon followed. Published in 1858, 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, William Stimson may have owned some of the first functional aquaria, 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, followed by others.^[11] The New York Aquarium Journal, first published in October 1876, is considered to be the world's first aquarium magazine.^[14]

In the Victorian era in the United Kingdom, 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, along with tanks of glass in metal frames.^[15] During the latter half of the 19th century, a variety of aquarium designs were explored, such as hanging the aquarium on a wall, mounting it as part of a window, 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, allowing artificial lighting as well as aeration, filtration, and heating of the water.^[17] Initially, 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, including innovations such as using a bicycle foot pump for aeration.^[19] Plastic shipping bags were introduced in the 1950s, making it easier to ship fish.^[20] The eventual availability of air freight, which allowed a much wider variety of fish, especially marine, to be successfully imported from distant regions of origin, consequently attracted new hobbyists.^[21] In the 1960s, a great breakthrough was reached. Metal frames made marine aquaria almost impossible due to corrosion, but the development of silicone sealant allowed the first all-glass aquaria. The frames remained, however, though purely for aesthetic reasons.^[15]

Aquarium keeping is now a popular hobby around the world, with about 60 million aquarists worldwide. In the United States, 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, it was estimated that 139 million freshwater fish and 9 million saltwater fish were kept in aquaria in the U.S.^[24] Similarly, 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, Asia, and North America. In the United States, 40 percent of aquarists maintain two or more tanks at any one time.

Design

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, availability, and reliability make the glass aquarium an industry standard for sizes up to about 1000 litres (250 gal). However, glass is brittle and has very little give before fracturing, though generally the sealant fails first.^[25] Aquaria come in a variety of shapes such as cuboid, hexagonal, angled to fit in a corner (L-shaped), bow-front (the front side curves outwards), and more.^[26] Fish bowls are generally either plastic or glass, either spherical or some other round configuration.

Acrylic aquaria are also available and are the primary competitor with glass. Acrylics are stronger than glass, 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, such as hexagonal.^[15] Compared to glass, acrylics are easy to scratch; care must be taken with organisms with shells and teeth.^[25]

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

Large aquaria might use stronger materials such as fiberglass-reinforced plastics. However, 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, sinks, and even toilets. Another such example is the Macquarium, 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, circular water flow with a lack of physical objects.^[28] Originally a German design (kreisel means spinning top), the tank is designed to have no sharp corners, and keeps the housed animals away from the plumbing. Water moving into the tank gives a gentle flow that keeps the inhabitants suspended, 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, a perfectly circular tank has a circular, submerged, lid. Pseudokreisels, have a curved bottom surface and a top surface flat, 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, and the surface of the water acts as the continuation of circular flow.

Aquarium size and volume

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, 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, reef aquaria under 100 litres (20 gal) earn a special place in the aquarium hobby; these aquaria, termed nano reefs, are known to be more difficult due to their small water volume. Practical limitations, most notably the weight (One litre of fresh water has a mass of 1 kilogram (8.3 lb gal^-1), and salt water is even denser) and internal water pressure (requiring thick, strong glass siding) of a large aquarium, keep most home aquaria to a maximum of around 1 cubic metre in volume (1000 kg or 2200 lb). Indeed, larger aquariums can even threaten the floor beneath the aquarium.^[26] Some dedicated aquarists, however, have been known to construct custom aquaria of up to many thousands of litres, 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, for example, features an individual aquarium of 7.7 million litres (2 million gallons).

Components

The typical hobbyist aquarium includes a filtration system, an artificial lighting system, and a heater or chiller depending on the inhabitants of the aquarium. Many aquaria incorporate a hood, 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, 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, and various designs and combinations are used.^[32]

Aquarium heaters combine a heating element with a thermostat, allowing an aquarist to regulate water temperature at a level above that of the surrounding air, whereas coolers and chillers (refrigeration devices) are for use in cold water aquaria, or anywhere the ambient room temperature is above the desired tank temperature.^[26] A variety of different thermometers are used, such as the glass alcohol thermometers, adhesive external plastic strip thermometers, and even battery-powered LCD thermometers.^[26] In addition, 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, lighting conditions, density of floating and rooted plants, placement of bogwood, creation of caves or overhangs, type of substrate, 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, they must be strong as well as level. A tank that is not level may distort, leak, or crack.^[26] These are often built like cabinets to allow storage, 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, this may void certain warranties.

Aquarium classifications

From the outdoor ponds and glass jars of antiquity, 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, to the huge public aquaria that can simulate entire marine ecosystems. A variety of different aquarium types exist; for the most part, 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.^[33] Marine aquaria are generally more difficult to setup and maintain than freshwater aquaria. Along with fish species, marine aquaria frequently feature a diverse range of invertebrates.^[33][32] Brackish water aquaria combine elements of both marine and freshwater fishkeeping.^[33] Fish kept in brackish water aquaria generally come from habitats with varying salinity, such as mangroves and estuaries. Certain subtypes of aquaria also exist within these types, such as the reef aquarium, 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.^[33] However, the coldwater aquarium is also popular, which often includes fish such as goldfish.^[33] Aquaria may be grouped by their species selection. The community tank is the most common type of aquarium kept today, where several non-aggressive species are housed peacefully together. Aggressive tanks, in contrast, house a limited number of species that can be aggressive toward other fish, or are able to withstand aggression well. Species or specimen tanks usually only house one fish species, along with plants, 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, such as the electric eel, as an extreme example. Some tanks of this sort are used simply to house adults for breeding. In these aquaria, the aquarium fish, invertebrates, and plants may or may not originate from the same geographic region, but generally tolerate similar water conditions.

Ecotype, ecotope, or biotope aquaria is another type based on species selection. In it, an aquarist attempts to simulate a specific ecosystem found in the natural world, bringing together fish, invertebrate species, 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, 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, and also usually serves as the healthiest possible artificial environment for the tank's occupants.

Public aquaria

Main article: 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, 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, including sharks or beluga whales. Dolphinariums are aquaria specifically for housing dolphins. Aquatic and semiaquatic animals, including otters and penguins, 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.

See also

• Fishkeeping
• Aquascaping
• List of freshwater aquarium fish species
• List of freshwater aquarium plant species
• List of freshwater aquarium invertebrate species
• List of freshwater aquarium amphibian species
• List of brackish aquarium fish species
• List of marine aquarium fish species
• List of aquarium diseases

References

External links

Aquarium at the Open Directory Project

•  • [ e] Zoos, aquaria and aviaries
Zoo Public aquarium Aviary Menagerie Oceanarium Tourist attraction Safari park List of zoos List of aquaria List of zoo associations Animals in captivity Environmental enrichment Endangered species Conservation biology Biodiversity Endangered species Extinction In-situ conservation Ex-situ conservation Frozen zoo Wildlife conservation Zoology

Aquarium and Fishkeeping Hobby
Types:	Freshwater aquarium • Marine aquarium • Brackish water aquarium • Community tank • Biotope • Reef aquarium • Nano reef
Aquarium equipment and furniture:	Filter • Berlin Method • Protein skimmer • Deep sand bed • Heater • Refugium • Calcium reactor • Bogwood and Driftwood • Airstone • Live rock • Substrate • Fishcam • Aquarium fish feeder
Fish terms:	Hardy fish • Dither fish • Algae eater • Bottom feeder • Tropical fish • Coldwater fish • Painted fish
Fish food:	Flake food • Feeder fish • Bloodworms • Brine shrimp • Tubifex tubifex • Daphnia • Infusoria
Lists:	List of freshwater aquarium fish species • List of freshwater aquarium plant species • List of freshwater aquarium invertebrate species • List of marine aquarium fish species • List of marine aquarium invertebrate species • List of brackish aquarium fish species • List of aquarium diseases
Other terms:	Aquascaping • Spawning triggers • Reef safe • Macquarium • Bath treatment
Aquarium magazines:	Practical Fishkeeping • Tropical Fish Hobbyist • Koi
Aquarium related companies:	Tetra • sera • EHEIM GmbH & Co. KG • Hagen