User:Jaspergeli/Fish keeping

Fish keeping is a popular hobby, practiced by aquarists, concerned with keeping fish in an aquarium. There is also a piscicultural fish keeping industry, as a branch of agriculture.

Fishes that are kept are almost in class Actinopterygii, the bony fishes, so in this case, it refers to keeping fishes that are members of the class Actinopterygii. Even "false" fish harvested in fisheries, such as molluscs, crustaceans, and any aquatic animal which is harvested. This means any aquatic animal is referred to as "fish", so it depends on how you will use it.

Types of fish keeping systems
fish keepers are often known as "aquarists" since many of them are not solely interested in keeping fish. The hobby can be broadly divided into three specific disciplines, depending on the type of water the fish originate from: fresh water, brackish water, and salt water or marine fish keeping.

Fresh water


Fresh water fish keeping is by far the most popular branch of the hobby, with even small pet stores, often selling a variety of fresh water fish, such as Cyprinins, guppies, and angelfish. While most fresh water aquaria are community tanks containing a variety of compatible species, single-species breeding aquaria are also popular. Livebearers such as mollies and guppies are among those most easily raised in captivity, but aquarists also regularly breed many types of cichlid, catfish, characids, cyprinids, and killifish.

Many fish keepers create fresh water aquascapes where the focus is on aquatic plants as well as fish.

Garden ponds are in some ways similar to fresh water aquaria, but are usually much larger and exposed to ambient weather. In the tropics, tropical fish can be kept in garden ponds. In the temperate zone, certain species in Cyprinidae particularly in Cyprininae, more particularly in Cyprinini work better than most fishes.

Salt water
Marine aquaria have more specific needs and requirements to maintain, and the livestock is generally more expensive. As a result, this branch tends to attract more experienced fish keepers. Marine aquaria can be exceedingly beautiful, due to the attractive colors and shapes of the corals and the coral reef fish they host. Temperate zone marine fish are not as commonly kept in home aquaria, primarily because they do not thrive at room temperature. Coldwater aquaria must provide cooler temperature via a cool room (such as an unheated basement) or a use of a refrigeration device known as "chiller".

Marine aquarists often attempt to recreate a coral reef in their aquaria using large quantities of living rock, calcareous rocks encrusted with coralline algae, sponges, worms, and other small marine organisms. Larger corals, as well as shrimps, crabs, echinoderms, and molluscs are added later on, once the aquarium has matured, as well as a variety of small fish. Such aquaria are sometimes called reef tanks.

Brackish water
Brackish water aquaria combine elements of the other types, with salinity that must stay between that of fresh water and seawater. Brackish water fish come from habitats with varying salinity, such as mangroves and estuaries, and do not thrive if kept permanently in fresh water. Although brackish water aquaria are not necessarily familiar to inexperienced aquarists, many species prefer brackish water, including some mollies, many gobies, some pufferfish, monos, and scats.

Aquarium maintenance
Ideal aquarium ecology reproduces the balance found in nature in the isolated system|closed system of an aquarium. In practice, it is virtually impossible to maintain a perfect balance. As an example, a balanced predation|predator-prey relationship is nearly impossible to maintain in even the largest aquaria. Typically, an aquarium keeper must actively maintain balance in the small ecosystems that aquaria provide.

Balance is facilitated by larger volumes of water which dilute the effects of a systemic shock. For example, the death of the only fish in a 10 l tank causes dramatic changes in the system, while the death of that same fish in a 400 l tank that holds many fish may create only a minor imbalance. For this reason, hobbyists often favor larger tanks whenever possible, as they require less intensive attention. This same concept extends to the filtration system as well, external (outside of the tank) systems in particular. Generally speaking, the larger the filtration system depending on its configuration, the more capable it will be of properly maintaining an aquatic environment. External filtration systems provide the added benefit of increasing the overall volume of water and its dilution effect. For example, a 190 l aquarium with an external filter that holds 40 l creates a 230 l aquatic system, and increase of over twenty percent.

A variety of biogeochemical cycle|nutrient cycles is important in the aquarium. Dissolved oxygen enters at the surface water-air interface through agitation or what would be observed as Wind wave|waves in a natural environment, and Carbon dioxide escapes into the air. The phosphate cycle is an important, although often overlooked, nutrient cycle. Sulfur, iron, and micronutrients enter the system as food and exit as waste. Appropriate handling of the nitrogen cycle, along with a balanced food supply and consideration of biological loading, is usually enough to keep these nutrient cycles in adequate equilibrium.

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 interact with their environment. Salt content, or salinity, is the most basic classification of water conditions. An aquarium may have fresh water (salinity below 0.5 PPT), simulating a lake or river environment; brackish water (a salt level of 0.5 to 30 PPT), simulating environments lying between fresh and salt, such as estuary|estuaries; and salt water or seawater (a salt level of 30 to 40 PPT), simulating an ocean or sea environment. Even higher salt concentrations are maintained in specialized tanks for raising brine organisms.

Several other water characteristics result from dissolved materials in the water and are important to the proper simulation of natural environments. salt water is typically alkaline, while the pH of fresh water varies. "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. Chemical oxygen demand|Dissolved organic content and dissolved gases content are also important factors.

Home aquarists typically use modified tap water supplied through their local water supply network. Because of the chlorine used to disinfectant|disinfect drinking water supplies for human consumption, tap water cannot be immediately used. 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 to dissipate. However, chloramine became popular in water treatment because it stays longer in the water. Additives are available to remove chlorine or chloramine and suffice to make the water ready. Brackish or salt water aquaria require the addition of a mixture of salts and other minerals.

More sophisticated aquarists may modify the water's alkalinity, hardness, or dissolved content of organics and gases. This can be accomplished by additives such as sodium bicarbonate to raise pH. Some aquarists Water filter|filter or purify their water using one of two processes: purified 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 easy access to water that requires only minimal treatment.

Water temperature 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 maintain an average temperature of about 25 C, it is much more common, and tropical fish are among the most popular aquarium denizens. Cold water aquaria maintain temperatures below the room temperature. More important than the range is temperature consistency; most organisms are not accustomed to sudden changes in temperatures, which can cause shock (biology)|shock and lead to disease. Water temperature can be regulated with a combined thermometer and heating or cooling unit.

Water movement can also be important in accurately simulating a natural ecosystem. Fish may prefer anything from nearly still water up to swift, simulated current (fluid)|currents. Water movement can be controlled through the use of aeration from air pumps, powerhead (pump)|powerhead pumps, and careful design of water flow (such as the location of filtration system points of inflow and outflow).

Nitrogen cycle
Fish are animals and generate waste as they metabolize food, which aquarists must manage. Fish, invertebrates, fungus|fungi, and some bacteria excrete nitrogen in the form of ammonia (which converts 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 above a certain concentration.

The process
A well-balanced tank contains organisms that metabolism|metabolize the waste products of other inhabitants. Nitrogen waste is metabolized in aquaria by a type of bacteria known as nitrification|nitrifiers (genus Nitrosomonas). Nitrifying bacteria metabolize ammonia into nitrite. Nitrite is also highly toxic to fish in low concentrations. Another type of bacteria, genus Nitrospira, on–converts nitrite into less–toxic nitrate. (Nitrobacter bacteria were previously believed to fill this role and appear in "jump start" kits. 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 is plentiful.) This process is known in the aquarium hobby as the nitrogen cycle.

In a planted aquarium, aquatic plants also metabolize Ammonium#Biology|ammonium and nitrate as nutrients, removing them from the water column primarily through leaf surfaces. Plants remove some nutrients through their roots, either in or at the substrate level or via aerial roots floating in the water. Additional nitrogen and other nutrients are also made available for root uptake by decomposing organic matter in the substrate as well as the breakdown of wikt:mulm|mulm. While very small amounts of rotting foliage may be allowed to decompose and cycle nitrogen back into a planted aquarium, in practice aquarists will prune and remove substantial amounts of plant litter.

Maintaining the nitrogen cycle
Although called the nitrogen "cycle" by hobbyists, in aquaria the cycle is not complete: nitrogen must be added (usually indirectly through food) and nitrates must be removed at the end. Nitrogen bound up in plant matter is removed when the plant grows too large.

Hobbyist aquaria typically do not have the requisite bacteria needed to detoxify nitrogen waste. This problem is most often addressed through filtration. Activated carbon filters absorb nitrogen compounds and other toxins from the water.

Biological filters provide a medium specially designed for colony (biology)|colonization by the desired nitrifying bacteria. Activated carbon and other substances, such as ammonia absorbing resins, stop working when their carbon filter|pores fill, so these components have to be replaced with fresh stocks periodically.

New aquaria often have problems associated with the nitrogen cycle due to insufficient beneficial bacteria, which is known as "New Tank Syndrome". Therefore, new tanks have to mature before stocking them with fish. There are three basic approaches to this: the Fishless cycling|fishless cycle, the silent cycle, and slow growth.


 * Tanks undergoing a "fishless cycle" have no fish. Instead, the keeper adds ammonia to feed the bacteria. During this process, ammonia, nitrite, and nitrate levels measure progress.
 * The "silent cycle" involves adding fast-growing plants and relying on them to consume the nitrogen, filling in for the bacteria work until their number increases. Anecdotal reports indicate that such plants can consume nitrogenous waste so efficiently that the ammonia and nitrite spikes that occur in more traditional cycling methods are greatly reduced or undetectable.
 * "Slow growth" entails slowly increasing the fish population over 6 to 8 weeks, giving bacteria time to grow and reach a balance with the increasing waste production.

Adding too many fish too quickly or failing to allow enough time for the bacteria colony to establish itself in the filter media can lead to ammonia stress. This is not always fatal but can result in the death of aquarium fish. A few days after adding hardy fish for the cycling process, it is essential to look out for the key signs of ammonia stress. These include a lack of movement and appetite, inflammation and redness of the gills, fins, and body, and occasionally gasping for air at the water's surface. The latter can also be attributed to poor aeration, which can be negated by the inclusion of an air pump or spray bar in the setup.

The largest bacterial populations inhabit the filter; efficient filtration is vital. Sometimes, simply cleaning the filter is enough to seriously disturb the aquarium's balance. Best practice is to flush mechanical filters using compatible water to dislodge organic materials while preserving bacteria populations. Another safe practice involves cleaning only one-half of the filter media every time the filter or filters are serviced to allow the remaining bacteria to repopulate the cleaned half.

Tank capacity
File:Small aquarium.jpg|thumb|300px|A fresh water aquarium with a group of Tetras Biological loading is a measure of the burden placed on the aquarium ecosystem by its living inhabitants. Higher biological loading represents a more complicated ecology, which makes equilibrium easier to imbalance. The surface area of water exposed to air limits Oxygen saturation|dissolved oxygen. The population of nitrifying bacteria is limited by the available physical space which includes all surfaces in the aquarium such as the inner facing sides and the surface of rock substrate and any objects such as large rocks or pieces of wood.

Tank size
Fish capacity is a function of aquarium size. Limiting factors include the availability of oxygen in the water and the rate at which the Filter (aquarium)|filter can process waste. Aquarists apply rules of thumb estimating appropriate population size; the examples below are for small fresh water fish. Larger fresh water fish and most marine fishes need much more generous allowances. Some aquarists claim that increasing water depth beyond some relatively shallow minimum does not affect capacity.


 * 2 liters of water for each centimeter of fish length.
 * 25 square centimeters of surface area per centimeter of fish length.

Experienced aquarists warn against mechanically applying these rules because they do not consider other important issues such as growth rate, activity level, social behavior, and such. Once the tank nears capacity, the best practice is to add the remaining fish over a period of time while monitoring water quality.

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. Capacity can also be increased with the addition of external filtration which increases the total volume of water in the aquatic system.

Other factors
Other variables affect tank capacity. Smaller fish consume more oxygen per unit of body weight than larger fish. Anabantoidei|Labyrinth fish can breathe atmospheric oxygen and need less surface area (however, some are territorial, and do not tolerate crowding). Barb (fish)|Barbs require more surface area than tetras of comparable size. The presence of waste materials presents itself as a variable as well. Decomposition consumes oxygen, reducing the amount available for fish. Oxygen dissolves less readily in warmer water, while warmer water temperature increase fish activity levels, which in turn consume more oxygen.