in California displaying a simulated
kelp forest ecosystem Ideal aquarium
ecology reproduces the balance found in nature in the
closed system of an aquarium. In practice, it is virtually impossible to maintain a perfect balance. As an example, a balanced
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. Basic aquarium maintenance should generally be performed weekly to maintain optimum conditions for fish and plants. 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 tank causes dramatic changes in the system, while the death of that same fish in a 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 aquarium with an external filter that holds creates a aquatic system, an increase of over twenty percent. A variety of
nutrient cycles is important in the aquarium. Imitating natural waves that would be found in natural bodies of water allows
dissolved oxygen to be dispersed, causing the release of
carbon dioxide. There are plenty of other vital processes and nutrients that are necessary for an aquarium to thrive. Nutritional cycles such as the
phosphate and
nitrogen cycle allow essential elements to support a stable environment. Consumption and waste both contribute greatly to these systems, including
sulfur,
iron, and other
micronutrients. Appropriate handling of these factors, along with a balanced food supply and consideration of biological loading, is a requirement to keep these nutrient cycles in adequate equilibrium.
Water conditions The
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. Depending on the water system that an aquarist chooses, maintaining the proper range of salt content is essential for these ecosystems to survive and to properly reflect conditions that exist within a natural system. These ranges and simulations include
freshwater (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
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. Saltwater is typically
alkaline, while the
pH of fresh water varies. "Hardness" measures overall dissolved mineral content;
hard or soft water may be preferred. Hard water is usually alkaline, while soft water is usually neutral to acidic. Ammonia is toxic to fish and other aquatic life in large quantities and that is why many fish keepers purchase testing kits to monitor the levels of ammonia in their water as well as monitoring nitrites and nitrates which are also part of the nitrogen cycle. Ammonia is produced from fish waste and uneaten food, after this is created it is broken down into nitrites by beneficial bacteria that is present in a properly cycled aquarium. Nitrites are then further broken down into the less toxic nitrates which can be absorbed by aquarium plants and nitrates absorbing filter media. Aquarists also use water changes as a way to keep these toxins under control by removing water from the aquarium and vacuuming fish waste and food from the gravel and replacing it with fresh, treated water.
The process A well-balanced tank contains organisms that
metabolize the waste products of other inhabitants.
Nitrogenous waste is metabolized in aquaria by a group of
bacteria known as
nitrifiers (genus
Nitrosomonas). Nitrifying bacteria metabolize ammonia into
nitrite, which is highly toxic to fish, even at low concentrations. Another type of bacteria (genus
Nitrospira), converts this nitrite into the less toxic compound,
nitrate. This process represents a portion of the
nitrogen cycle. In a planted aquarium, aquatic plants also metabolize
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
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
colonization by the desired nitrifying bacteria. Activated carbon and other substances, such as ammonia absorbing
resins, stop working when their
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 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 s,
neon tetras and
glowlight 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
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 can process waste. Aquarists apply rules of thumb estimating appropriate population size; the examples below are for small freshwater fish. Larger freshwater 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. • 30 square centimetres of surface area per centimetre of fish length (12 square inches per inch). 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.
Labyrinth fish can breathe atmospheric oxygen and need less surface area (however, some are territorial, and do not tolerate crowding).
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. == Fishkeeping industry ==