Aquarium 3185 225828813 2008-07-15T16:18:22Z Antandrus 57658 Reverted edits by [[Special:Contributions/OrgasGirl|OrgasGirl]] ([[User talk:OrgasGirl|talk]]) to last version by Arpingstone {{alternateuses}} [[Image:Amaterske akvarium.jpg|right|thumb|A freshwater aquarium with plants and tropical fish]] [[Image:Home aqua 240 litres.png|thumb|A well planted aquarium (240&nbsp;l)]] An '''aquarium''' (plural ''aquariums'' or ''aquaria'') is a [[vivarium]] consisting of at least one transparent side in which [[water]]-dwelling [[plant]]s or [[animal]]s are kept. [[fishkeeping|Fishkeepers]] use aquaria to keep [[fish]], [[invertebrate]]s, [[amphibian]]s, [[marine mammal]]s, and aquatic plants. The term combines the Latin root ''aqua'', meaning water, with the suffix ''-arium'', meaning "a place for relating to".<ref>{{cite web | url = http://www.m-w.com/dictionary/aquarium | title = Definition of aquarium | publisher = Merriam-Webster Online Dictionary | accessdate = 2007-04-03 }}</ref> An '''aquarist''' owns or maintains an aquarium, typically constructed of [[glass]] or high-strength [[plastic]]. [[Cuboid]] aquaria are also known as '''fish tanks''' or simply '''tanks''', while [[bowl (vessel)|bowl]]-shaped aquaria are also known as '''fish bowls'''. Size can range from a small glass bowl to immense public aquaria. Specialised equipment maintains appropriate water quality and other characteristics suitable for the aquarium's residents. == History and popularization == In the [[Roman Empire]], the first fish to be brought indoors was the [[Barbel (fish species)|sea barbel]], which was kept under guest beds in small tanks made of marble. Introduction of glass panes around the year 50 allowed Romans to replace one wall of marble tanks, improving their view of the fish. In 1369, the [[Emperor of China|Chinese Emperor]], [[Hongwu]], established a [[porcelain]] company that produced large porcelain tubs for maintaining [[goldfish]]; over time, people produced tubs that approached the shape of modern fish bowls.<ref>{{cite book | last = Brunner | first = Bernd | title = The Ocean at Home | publisher = Princeton Architectural Press | date = 2003 | location = New York | isbn = 1-56898-502-9 | pages = 21-22}}</ref> Leonhard Baldner, who wrote ''Vogel-, Fisch- und Tierbuch'' (Bird, Fish, and Animal Book) in 1666, maintained [[weather loach]]es and [[newt]]s.<ref name = "duqmbv">Brunner, B: ''The Ocean at Home'', page 25</ref> 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, he soon housed real animals. In 1838, [[Félix Dujardin]] noted owning a [[saltwater aquarium]], though he did not use the term.<ref name=Brunner35>Brunner, B: ''The Ocean at Home'', page 35</ref> In 1846, Anna Thynne maintained [[Scleractinia|stony corals]] and [[seaweed]] for almost three years, and was credited as the creator of the first balanced marine aquarium in London.<ref>Brunner, B: ''The Ocean at Home'', pages 35-36</ref> At about the same time, Robert Warington experimented with a 13-gallon container, which contained goldfish, [[Vallisneria|eelgrass]], and [[snail]]s, creating one of the first stable aquaria; he published his findings in 1850 in the [[Chemical Society|Chemical Society's]] [[scientific journal|journal]].<ref>Brunner, B: ''The Ocean at Home'', page 36</ref> [[Image:Pike aquarium c1908.jpg|thumb|right|[[Esox|Pike]] in an aquarium c. 1908, at the Detroit Aquarium, Belle Isle Park.]] 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 [[The Great Exhibition|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.<ref>Brunner, B: ''The Ocean at Home'', pages 99</ref> [[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.<ref>Brunner, B: ''The Ocean at Home'', page 38</ref> In the 1850s, the aquarium became a fad in the United Kingdom.<ref>Brunner, B: ''The Ocean at Home'', page 57</ref> [[Image:What an Aquarium Should Be.png|thumb|left|"What an Aquarium Should Be" - an 1876 British engraving.]] Germans soon rivaled the British in their interest. In 1854, an anonymous author had two articles published about the saltwater aquaria of the United Kingdom: ''Die Gartenlaube'' (The Garden House) entitled ''Der Ocean auf dem Tische'' (The Ocean on the Table). 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.<ref>Brunner, B: ''The Ocean at Home'', pages 60-61</ref> During the 1870s, some of the first [[Aquarium fish clubs|aquarist societies]] were appearing in Germany.<ref name=Brunner75>Brunner, B: ''The Ocean at Home'', page 75</ref> 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.<ref>Brunner, B: ''The Ocean at Home'', page 69</ref> 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.<ref>Brunner, B: ''The Ocean at Home'', page 71</ref> The first aquarist society in the United States was founded in [[New York City]] in 1893, followed by others.<ref name=Brunner75/> The ''New York Aquarium Journal'', first published in October 1876, is considered to be the world's first aquarium magazine.<ref>Brunner, B: ''The Ocean at Home'', pages 76-77</ref> 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 (resin)|pitch]] coating). The bottom would be made of [[slate]] and heated from below.<ref name=Sanford>{{cite book | title = Aquarium Owner's Guide | last = Sanford | first = Gina | publisher = [[DK Publishing]] | location = New York | date = 1999 | pages = 9-13 | isbn = 0-7894-4614-6}}</ref> More advanced systems soon began to be introduced, along with tanks of glass in metal frames.<ref name=Sanford/> 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]].<ref>Brunner, B: ''The Ocean at Home'', pages 86-89</ref> Aquaria became more widely popular as houses had an electricity supply after [[World War I]]. [[Electricity]] allowed artificial lighting as well as [[aeration]], [[filtration]], and heating of the water.<ref>Brunner, B: ''The Ocean at Home'', page 93</ref> Initially, amateur aquarists kept native fish (with the exception of goldfish); the availability of exotic species from overseas further increased the popularity of the aquarium.<ref>Brunner, B: ''The Ocean at Home'', page 78</ref> Jugs made from a variety of materials were used to import fish from overseas, with a [[bicycle pump|bicycle foot pump]] for aeration.<ref>Brunner, B: ''The Ocean at Home'', pages 82-83</ref> Plastic shipping bags were introduced in the 1950s, making it easier to ship fish.<ref>Brunner, B: ''The Ocean at Home'', page 82</ref> The eventual availability of air freight, allowed fish to be successfully imported from distant regions.<ref name = "duqmbv"/> In the 1960s metal frames made [[marine aquarium|marine aquaria]] almost impossible due to corrosion, but the development of [[tar]] and [[silicone]] sealant allowed the first all-glass aquaria made by Martin Horowitz in Los Angeles, CA. The frames remained, however, though purely for aesthetic reasons.<ref name=Sanford/> There are now around 60 million aquarists worldwide.{{Fact|date=April 2007}} In the United States, aquarium keeping is the second-most popular hobby after [[stamp collecting]].<ref name="baensch">{{cite book |last=Riehl |first=Rüdiger. Editor. |coauthors=Baensch, HA |title=Aquarium Atlas |year=1996. 5th Edn. |publisher=Tetra Press |location=Germany |isbn=3-88244-050-3}}</ref> In 1999 it was estimated that over nine million U.S. households own an aquarium. Figures from the 2005/2006 APPMA National Pet Owners Survey report that Americans own approximately 139 million freshwater fish and 9.6 million saltwater fish.<ref>{{cite web|url=http://directmag.com/mag/marketing_aquarium_hobbyists/|title=Aquarium Hobbyists|last=Emerson|first=Jim|date=1999-08-01|accessdate=2007-05-02}}</ref><ref>{{cite web|url=http://www.appma.org/newsletter/may2005/npos.html|title=National Pet Owners Survey|publisher=American Pet Products Manufacturers Association|year=2005|accessdate=2007-05-02}}</ref> Estimates of the numbers of fish kept in aquaria in Germany suggest at least 36 million.<ref name="baensch"/> 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.{{Fact|date=April 2007}} == Design == [[Image:Aquarium 60cm.JPG|thumb|right|An 80 litre home aquarium.]] === Materials === Most aquaria consist of [[glass]] panes bonded together by [[silicone]], with plastic frames that are attached to the upper and lower edges for decoration. The glass aquarium is standard for sizes up to about 1000&nbsp;[[litre]]s (250&nbsp;[[gallon|gal]]). However, glass is brittle and has very little give before fracturing, though generally the sealant fails first.<ref name=Adey>{{citation|title=Dynamic Aquaria|last1 = Adey|first1 = Walter H.|last2 = Loveland|first2 = Karen|publisher=Academic Press|location=San Diego|date=1991|isbn=0-12-043792-9}}</ref> Aquaria come in a variety of shapes such as [[cuboid]], [[hexagonal prism|hexagonal]], angled to fit in a corner (L-shaped), bow-front (the front side curves outwards).<ref name=Sanford2>{{cite book | title = Aquarium Owner's Guide | last = Sanford | first = Gina | publisher = [[DK Publishing]] | location = New York | date = 1999 | pages = 162-169 | isbn = 0-7894-4614-6}}</ref> Fish bowls are generally either plastic or glass, either spherical or some other round configuration. [[acrylic glass|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).<ref name=Adey/> Acrylic allows for the formation of unusual shapes, such as hexagonal.<ref name=Sanford/> Compared to glass, acrylics are easy to scratch; care must be taken with organisms with shells and teeth.<ref name=Adey/> [[Laminated glass]] might be used, which combines the advantages of both glass and acrylic.<ref name=Adey/> Large aquaria might use stronger materials such as [[fiberglass]]-reinforced [[plastic]]s. However, this material is not transparent.<ref name=Adey/> 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.<ref name=Adey/> === Styles === 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]].<ref>{{cite web|url=http://www.cs.tut.fi/~ace/macquarium.html|title=The Original MacQuarium|first=Andy|last=Ihnatko|date=1992|accessdate=2007-04-04}}</ref> A '''kreisel tank''' is a [[circle|circular]] aquarium designed to hold delicate animals such as [[jellyfish]]. These aquariums provide slow, circular water flow with a lack of physical objects.<ref>{{cite web|url=http://www.advancedaquarist.com/issues/dec2004/lines.htm|title=Delicatessen Part I: Creating a system for rare and delicate animals|last=Blundell|first=Adam|publisher=Advanced Aquarist's Online Magazine|date=December 2004|accessdate=2007-04-04}}</ref> Originally a German design (''kreisel'' means spinning top), the tank has 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 circular tank has a circular, submerged lid. Pseudokreisels have a curved bottom surface and a flat top surface, similar to the shape of either a "U" or a [[semicircle]].<ref>{{cite web | author = Wrobel, Dave |url=http://jellieszone.com/captivejellies.htm|title=Captive Jellies: Keeping Jellies in an Aquarium | publisher = The Jellies Zone |accessdate=2007-04-04}}</ref> 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=== [[Image:Male_whale_shark_at_Georgia_Aquarium.jpg|thumb|right|The large Georgia Aquarium houses a [[Whale shark]].]] An aquarium can range from a small glass bowl containing less than a [[litre]] (34&nbsp;[[Fluid ounce|fl.oz.]]) of water to immense public aquaria which can house entire ecosystems such as [[kelp forest]]s. Larger aquaria are typically recommended to hobbyists due to their resistance to rapid fluctuations of temperature and [[pH]], allowing for greater system stability.<ref name=Sanford2/> Reef aquaria under 100&nbsp;litres (20&nbsp;gal) have a special place in the aquarium hobby; these aquaria, termed [[nano reef]]s (when used in reefkeeping), have a small water volume.{{Fact|date=February 2008}}. Practical limitations, most notably the [[weight]] (one litre of fresh water has a mass of 1&nbsp;kilogram ({{nowrap|8.3 lb}} gal<sup>-1</sup>), and salt water is even denser) and internal [[fluid pressure|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 ({{nowrap|1,000 kg}} or {{nowrap|2,200 lb}}).<ref name=Sanford2/> Some aquarists, however, have constructed aquaria of up to many thousands of litres.<ref>{{cite web|url =http://www.cichlid-forum.com/articles/diy_1700g_tank_1.php|title = Building a 1700 gallon Shark Tank|publisher = cichlid-forum.com | publisher=Cichlid-Forum.com|last=Salvatori|first=Joe|accessdate=2007-04-03}}</ref><ref>{{cite web|url=http://www.monsterfishkeepers.com/forums/showthread.php?t=8952|title=Building My 50,000 Gallon Monster Mega Tank|publisher=MonsterFishKeepers.com|date=[[2005-10-30]]|accessdate=2007-04-04}}</ref> Aquaria within [[Public Aquarium|public aquariums]] designed for exhibition of large species or environments can be dramatically larger than any home aquarium. The [[Georgia Aquarium]], for example, features an individual aquarium of {{convert|6300000|USgal|m3}}. ==Components== [[Image:Aquarium.png|thumb|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 will include 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.<ref name=Sanford2/> Combined biological and mechanical aquarium [[Filter (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 nitrogen being at the expense of aquatic plants. Particulates incorporated into the filter can provide energy for [[microbes]] and [[aquatic fungus|sponges]] that do things like [[nitration]]. Filtration systems are often the most complex component of home aquaria.<ref name=dakin>{{cite book|title=The Macmillan book of the Marine Aquarium|publisher=[[Macmillan Publishers|Macmillan Publishing Company]]|location=New York|last=Dakin|first=Nick|year=1992|ISBN = 0-02-897108-6}}</ref> [[Heater (aquarium)|Aquarium heater]]s 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.<ref name=Sanford2/> [[Thermometer]]s used include glass alcohol thermometers, adhesive external plastic strip thermometers, and battery-powered LCD thermometers.<ref name=Sanford2/> In addition, some aquarists use air pumps attached to [[airstone]]s 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.<ref name=Adey/> 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 (aquarium)|substrate]], and other factors (including an aquarium's positioning within a room) can all affect the behavior and survival of tank inhabitants. An aquarium can be placed on an aquarium stand. Because of the weight of the aquarium, a stand must be strong as well as level. A tank that is not level may distort, leak, or crack.<ref name=Sanford2/> 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.<ref name=Sanford2/> Some sources say that [[polystyrene]] should be placed under the aquarium as a safety precaution.<ref name=Sanford2/> ==Aquarium maintenance== [[Image:KelpAquarium.jpg|thumb|right|A 335,000&nbsp;U.S. gallon (1.3 million litre) aquarium at the [[Monterey Bay Aquarium]] in California displaying a [[kelp forest]] ecosystem]] Large volumes of water enable more stability in a tank by diluting effects from death or contamination. Any event that perturbs the system pushes an aquarium away from equilibrium; the more water that is contained in a tank, the easier such a [[systemic shock]] is to absorb, as the effects of that event are diluted. For example, the death of the only fish in a three&nbsp;U.S. gallon tank (11&nbsp;L) causes dramatic changes in the system, while the death of that same fish in a 100&nbsp;U.S. gallon (400&nbsp;L) tank with many other fish in it represents only a minor change in the balance of the tank. For this reason, hobbyists often favor larger tanks, as they are more stable systems requiring less attention to the maintenance of equilibrium. There are a variety of [[nutrient cycle]]s that are important in the aquarium. Dissolved oxygen enters the system at the surface water-air interface or through the actions of an air pump. Carbon dioxide escapes the system into the air. The phosphate cycle is an important, although often overlooked, nutrient cycle. Sulfur, iron, and micronutrients also cycle through the system, entering as food and exiting as waste. Appropriate handling of the [[nitrogen cycle]], along with supplying an adequately balanced food supply and considered biological loading, is enough to keep these other nutrient cycles in approximate equilibrium, but not forever. ===Water conditions=== The [[Solution|solute]] content of water is perhaps the most important aspect of water conditions, as [[total dissolved solids]] and other constituents can dramatically impact basic water chemistry, and therefore how organisms are able to interact with their environment. Salt content, or [[salinity]], is the most basic classification of water conditions. An aquarium may have [[fresh water]] (salinity below 500&nbsp;parts per million), simulating a lake or river environment; [[brackish water]] (a salt level of 500 to 30,000&nbsp;PPM), simulating environments lying between fresh and salt, such as [[estuary|estuaries]]; and salt water or [[sea water]] (a salt level of 30,000 to 40,000&nbsp;PPM), simulating an ocean or sea environment. Rarely, even higher salt concentrations are maintained in specialized tanks for raising brine organisms. Saltwater is typically alkaline, while the [[pH]] ([[alkali]]nity or [[acid]]icity) of fresh water varies more. Hardness measures overall dissolved mineral content; [[hard water|hard or soft water]] may be preferred. Hard water is usually alkaline, while soft water is usually neutral to acidic.<ref name=Axelrod/> [[Chemical oxygen demand|Dissolved organic content]] and dissolved gases content are also important factors. [[Image:Aquarium-Tank.jpg|right|thumb|An average home 10 gallon tropical freshwater aquarium.]] Home aquarists typically use tap water supplied through their local [[water supply network]] to fill their tanks. Because of the concentration of [[chlorine]] used to [[disinfection|disinfect]] drinking water supplies for human consumption, straight tap water cannot be used in the USA. In the past, it was possible to "condition" the water by simply letting the water stand for a day or two, which allows the [[chlorine]] time to dissipate.<ref name=Axelrod/> However, [[chloramine]] is now used more often as it is much stabler and will not leave the water as readily. Additives formulated to remove chlorine or chloramine are often all that is needed to make the water ready for aquarium use. Brackish or saltwater aquaria require the addition of a mixture of salts and other minerals, which are commercially available. More sophisticated aquarists may make other modifications to their base water source to modify the water's alkalinity, hardness, or dissolved content of organics and gases, before adding it to their aquaria. This can be accomplished by additives, such as sodium bicarbonate, to raise pH.<ref name=Axelrod/> Some aquarists will [[filter (water)|filter]] or purify their water prior to adding it to their aquarium. There are two processes used: [[deionized water|deionization]] or [[reverse osmosis]]. In contrast, public aquaria with large water needs often locate themselves near a natural water source (such as a river, lake, or ocean) in order to have access to water that does not require much further treatment. The [[temperature]] of the water forms the basis of one of the two most basic aquarium classifications: [[tropics|tropical]] vs. [[Coldwater fish|cold water]]. Most fish and plant species tolerate only a limited range of water temperatures: Tropical or warm water aquaria, with an average temperature of about {{nowrap|25 °C}} ({{nowrap|77 °F}}), are much more common. Cold water aquaria are those with temperatures below what would be considered tropical; some varieties of fish are better suited to this cooler environment. More important than the temperature range itself is the consistency in temperature; most organisms are not accustomed to sudden changes in temperatures, which could cause shock and lead to disease.<ref name=Axelrod/> Water temperature can be regulated with a combined [[thermostat]] and heater unit (or, more rarely, with a cooling unit). Water movement can also be important in accurately simulating a natural ecosystem. Aquarists may prefer anything from still water up to swift simulated [[current (fluid)|currents]] in an aquarium, depending on the conditions best suited for the aquarium's inhabitants. Water movement can be controlled through the use of aeration from air pumps, powerheads, and careful design of internal water flow (such as location of filtration system points of inflow and outflow). ===Nitrogen cycle=== [[Image:Aquarium Nitrogen Cycle.png|thumb|The nitrogen cycle in an aquarium.]] {{main|Nitrogen cycle}} Of primary concern to the aquarist is management of the biological [[waste]] produced by an aquarium's inhabitants. Fish, invertebrates, [[fungus|fungi]], and some bacteria excrete [[nitrogen]] waste in the form of [[ammonia]] (which will convert to [[ammonium]], in acidic water) and must then pass through the [[nitrogen cycle]]. Ammonia is also produced through the [[decomposition]] of plant and animal matter, including [[feces|fecal]] matter and other [[detritus]]. Nitrogen waste products become [[toxic]] to fish and other aquarium inhabitants at high concentrations.<ref name=Axelrod>{{cite book | title = Exotic Tropical Fishes | last = Axelrod | first = Herbert, R. | publisher = T.F.H. Publications. | year = 1996 | id = ISBN 0-87666-543-1}}</ref> ====The process==== A well-balanced tank contains organisms that are able to [[metabolism|metabolize]] the waste products of other aquarium residents. The nitrogen waste produced in a tank is metabolized in aquaria by a type of [[bacterium|bacteria]] known as [[nitrification|nitrifiers]] (genus ''[[Nitrosomonas]]''). Nitrifying bacteria capture ammonia from the water and metabolize it to produce [[nitrite]]. Nitrite is also highly toxic to fish in high concentrations. Another type of bacteria, genus ''Nitrospira'', converts nitrite into [[nitrate]], a less toxic substance to aquarium inhabitants. (''[[Nitrobacter]]'' bacteria were previously believed to fill this role, and continue to be found in commercially available products sold as kits to "jump start" the nitrogen cycle in an aquarium. While biologically they could theoretically fill the same niche as Nitrospira, it has recently been found that ''Nitrobacter'' are not present in detectable levels in established aquaria, while ''Nitrospira'' are plentiful.) This process is known in the aquarium hobby as the [[nitrogen cycle]]. In addition to bacteria, aquatic plants also eliminate nitrogen waste by metabolizing ammonia and nitrate. When plants metabolize nitrogen compounds, they remove nitrogen from the water by using it to build [[biomass]] that decays more slowly than ammonia-driven [[plankton]] already dissolved in the water. ====Maintaining the nitrogen cycle==== Although informally called the nitrogen cycle by hobbyists, it is in fact only a portion of a true cycle: nitrogen must be added to the system (usually through food provided to the tank inhabitants), and nitrates accumulate in the water at the end of the process, or become bound in the biomass of plants. This accumulation of nitrates in home aquaria requires the aquarium keeper to remove water that is high in nitrates, or remove plants which have grown from the nitrates. Aquaria kept by hobbyists often do not have the populations of bacteria needed to detoxify nitrogen waste from tank inhabitants. This problem is most often addressed through two [[filtration]] solutions: [[Activated carbon]] filters absorb nitrogen compounds and other [[toxins]] from the water, while biological filters provide a medium designed for [[colony (biology)|colonization]] by the desired nitrifying bacteria. Activated carbon and other substances, such as ammonia absorbing resines, will stop working when their pores get full, so these components have to be replaced with fresh stocks constantly. New aquaria often have problems associated with the nitrogen cycle due to insufficient number of beneficial bacteria, known as [http://www.bestfish.com/breakin.html "New Tank Syndrome"]. Therefore new tanks have to be matured before stocking them with fish. There are three basic approaches to this: the ''fishless cycle'' the ''silent cycle'' and ''slow growth''. No fish are kept in a tank undergoing a "fishless" cycle. Instead, small amounts of ammonia are added to the tank to feed the bacteria being cultured. During this process, [[ammonia]], [[nitrite]], and [[nitrate]] levels are tested to monitor progress. The "silent" cycle is basically nothing more than densely stocking the aquarium with fast-growing aquatic [[plant]]s and relying on them to consume the [[nitrogen]], allowing the necessary bacterial populations time to develop. According to anecdotal reports of aquarists specializing in planted tanks, the plants can consume nitrogenous waste so efficiently that the spikes in ammonia and nitrite levels normally seen in more traditional cycling methods are greatly reduced, if they are detectable at all. "Slow growth" entails slowly increasing the population of fish over a period of 6 to 8 weeks, giving bacteria colonies time to grow and stabilize with the increase in fish waste. The largest bacterial populations are found in the filter; efficient filtration is vital. Sometimes, a vigorous cleaning of the filter is enough to seriously disturb the biological balance of an aquarium. Therefore, it is recommended to rinse mechanical filters in an outside bucket of aquarium water to dislodge organic materials that contribute to nitrate problems, while preserving bacteria populations. Another safe practice consists of cleaning only one half of the filter media every time the filter or filters are serviced. ===Biological loading=== [[Image:Small aquarium.jpg|thumb|Nineteen litre aquarium]] Biological loading is a measure of the burden placed on the aquarium ecosystem by its living inhabitants. High biological loading in an aquarium represents a more complicated tank ecology, which in turn means that equilibrium is easier to perturb. In addition, there are several fundamental constraints on biological loading based on the size of an aquarium. The [[surface area]] of water exposed to air limits [[Oxygen saturation|dissolved oxygen]] intake by the tank. The capacity of nitrifying bacteria is limited by the physical space they have available to colonize. Physically, only a limited size and number of plants and animals can be fit into an aquarium while still providing room for movement. Simply, all kinds of biology decay, and biological loading refers to that rate of decay in proportion to tank volume. ====Calculating aquarium capacity==== An aquarium can only support a certain number of fish. [[Limiting factor]]s include the availability of oxygen in the water and the rate at which the filtration can process waste. Aquarists have developed [[rule of thumb|rules of thumb]] to [[estimate]] the number of fish that can be kept in an aquarium; the examples below are for small freshwater fish, larger freshwater fishes and most marine fishes need much more generous allowances. *3&nbsp;[[centimetre|cm]] of fish length per 4&nbsp;[[litre]]s of water (i.e., a 6&nbsp;cm-long fish would need about 8&nbsp;litres of water).<ref name="Ulrich Baensch">Ulrich Baensch, Tropical Aquarium Fish, Tetra, 1983</ref> *1&nbsp;[[centimetre|cm]] of fish length per 30&nbsp;[[square centimetre]]s of surface area.<ref name="Scott">Peter Scott, The Complete Aquarium, Dorling Kindersley, 1996, ISBN 0-7513-0427-1</ref> *1&nbsp;[[inch]] of fish length per [[gallon]] of water.<ref name="Ulrich Baensch"/> *1&nbsp;[[inch]] of fish length per 12&nbsp;[[square inch]]es of surface area.<ref name="Scott"/> Experienced aquarists warn against applying these rules too strictly because they do not consider other important issues such as growth rate, activity level, social behaviour, surface area of plant life, and so on.<ref>Chris Andrews, Adrian Exell, & Neville Carrington, The Interpet Manual of Fish Health, Salamander Books, 1988, ISBN 0-86101-368-9</ref> To some degree, establishing the maximum loading capacity of an aquarium depends upon slowly adding fish and monitoring water quality over time, essentially a [[trial and error]] approach. One emerging alternative to the trial and error approach is the use of computer programs that calculate an aquarium's stocking capacity based on many of the factors most authors are concerned about. These systems are experimental at present but have had a fair degree of success in accounting for situations that the more general guidelines cannot. No less, the current application of these systems is in helping aquarists figure out what will not work, but not necessarily a sure-fire method for figuring out what will work. <ref>http://board.fishchannel.com/Topic132702-5-1.aspx</ref> ====Factors affecting capacity==== Though many conventional methods of calculating the capacity of aquarium are based on volume and pure length of fish, there are other variables. One variable is differences between fish. Smaller fish consume more oxygen per gram of body weight than larger fish. Labyrinth fish, having the capability to breathe atmospheric oxygen, are noted for not needing as much surface area (however, some of these fish are territorial, and may not appreciate crowding). Barbs also require more surface area than tetras of comparable size.<ref name=Axelrod/> Oxygen exchange at the surface is an important constraint, and thus the surface area of the aquarium. Some aquarists go so far as to say that a deeper aquarium with more volume holds no more fish than a shallower aquarium of the same surface area. The capacity can be improved by surface movement and water circulation such as through aeration, which not only improves oxygen exchange, but also the decomposition of waste materials.<ref name=Axelrod/> The presence of waste materials presents itself as a variable as well. Decomposition in solution tends to consume oxygen. Oxygen dissolves less readily in warmer water; this is a double-edged sword as warmer temperatures make more active fish, which in turn consume even more oxygen. Stress due to temperature changes is especially obvious in coldwater aquaria where the temperature may swing from low temperatures to high temperatures on hotter days.<ref name=Axelrod/> Despite the complexity of the myriad of factors affecting stocking capacity, some individuals have tried to create spreadsheet programs to account for them. One such system is a program called "TheFishsheet" that accounts for filter size, surface area, agitation, aerobic bacteria, anaerobic bacteria, cleaning frequency and percentage removed, and remaining waste. Despite that this sytem is experimental, it has shown some success at predicting which aquarium systems will not work. No less, the creator of this system, John M. Johnson, Jr., cautions that it is not a guarantee for success--just a guidline that is more accurate than the length-based models mentioned previously. <ref>http://board.fishchannel.com/Attachment322.aspx</ref> ==Aquarium classifications== [[Image:58g aquascape.jpg|thumb|A planted freshwater aquarium]] 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 [[ecosystem]]s. One of ways to classify aquaria is their salinity. [[Freshwater aquarium|Freshwater aquaria]] are the most popular kind of aquarium due to their lower cost and ease of maintenance.<ref name=Sanford3>{{cite book | title = Aquarium Owner's Guide | last = Sanford | first = Gina | publisher = [[DK Publishing]] | location = New York | date = 1999 | pages = 180-199 | isbn = 0-7894-4614-6}}</ref> [[Marine aquarium|Marine aquaria]] generally require more complex equipment to set up and maintain than freshwater aquaria. Along with fish species, marine aquaria frequently feature a diverse range of [[invertebrates]].<ref name=Sanford3/><ref name=dakin/> [[Brackish water aquarium|Brackish water aquaria]] combine elements of both marine and freshwater fishkeeping.<ref name=Sanford3/> 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]].<ref name=Sanford3/> Another classification is by [[temperature]] range. Many aquarists maintain a [[tropical fish|tropical aquarium]] as these fish tend to be more colorful.<ref name=Sanford3/> However, the [[coldwater fish|coldwater aquarium]] is also popular, which may include fish such as [[goldfish]].<ref name=Sanford3/> [[Image:Aquarium fg01.jpg|thumb|A saltwater aquarium.]] 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. In these aquaria, the aquarium fish, [[invertebrate]]s, and [[aquatic plant|plants]] probably do not originate from the same geographic region, but generally tolerate similar water conditions. 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. 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, public aquaria use this approach in their exhibits whenever possible. This approach best simulates the experience of observing an aquarium's inhabitants in the wild. Matching a tank to the environment at the source of fish usually serves as the healthiest possible artificial environment for the tank's occupants. ==Public aquaria== [[Image:Georgia Aquarium - Ocean Voyager Tunnel Jan 2006.jpg|thumb|right|Tunnel at the world's largest aquarium, [http://www.georgiaaquarium.org Georgia Aquarium], USA.]] {{Main|Public aquarium}} 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 gallons of water and can house large species, including [[shark]]s or [[beluga]] whales. [[Dolphinarium]]s are aquaria specifically for housing dolphins. Aquatic and semiaquatic animals, including [[otter]]s and [[penguin]]s, 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]]. ==Virtual aquariums== A '''virtual aquarium''' is a [[computer program]] which uses [[3D graphics]] to reproduce an aquarium on a [[personal computer]]. The swimming fish are [[rendering engine|rendered]] in [[Real-time computer graphics|real time]], while the [[background]] of the tank is usually static. Objects on the floor of the tank may be mapped in simple [[plane]]s so that the fish may appear to swim both in front and behind them, but a relatively simple 3D map of the general shape of such objects may be used to allow the light and ripples on the surface of the water to cast realistic [[shadow]]s. Bubbles and water noises are common for virtual aquariums, which are often used as [[screensaver]]s. The number of each type of fish can usually be selected, often including other animals like [[starfish]], [[jellyfish]], [[seahorse]]s, and even [[sea turtles]]. Most companies that produce virtual aquarium software also offer other types of fish for sale via Internet [[download]]. Other objects found in an aquarium can also be added and rearranged on some software, like [[treasure chest]]s and giant [[clam]]s that open and close with air bubbles, or a bobbing [[deep-sea diving|diver]]. There are also usually features that allow the user to tap on the glass or put food in the top, both of which the fish will react to. Some also have the ability to allow the user to edit fish and other objects to create new varieties. ==See also== {{commonscat|Aquariology}} {{commons|Aquarium}} *[[Aquascaping]] *[[Association of Zoos and Aquariums]] (AZA) *[[Fishkeeping]] *[[List of aquarium diseases]] *[[List of brackish aquarium fish species]] *[[List of freshwater aquarium amphibian species]] *[[List of freshwater aquarium fish species]] *[[List of freshwater aquarium invertebrate species]] *[[List of freshwater aquarium plant species]] *[[List of marine aquarium fish species]] *[[Public aquariums]] ==References== {{Reflist|2}} ==External links== <!-- ==============================({{NoMoreLinks}})============================== --> <!-- DO NOT ADD MORE LINKS TO THIS ARTICLE UNLESS THEY CONFORM TO [[WP:EL]]. 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