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Keeping and caring for rainbowfishes in captivity is relatively simple as far as general aquarium conditions are concerned - they are one of the easiest fishes to maintain. All the same, rainbowfishes do have a number of basic requirements in order to survive from day to day, to breed and to maintain populations over the longer term. Rainbowfishes are living beings and require suitable habitat, proper nutrition, and a stress-free existence if they are to grow and remain healthy. A few of the hardier species may survive without any particular effort on your part. However, if you want to be successful at keeping rainbowfishes then you must make an effort to learn some basic aquarium principles to maintain and care for them.
Practical experience can only be gained through time and exposure to the aquarium environment. It's a combination of learning aquarium disciplines and experience that will make you a successful aquarist. The actual learning that is required is relatively easy and the rewards so much greater. Fishkeeping is a wonderful hobby and a great way to spend ones leisure time. However, more than a few fishkeepers have watched the inhabitants of an unhealthy aquarium die because they had failed to learn the basics. If you do not have time to learn the basics, then I suggest that you seriously reconsider the idea of keeping rainbowfishes in captivity.
Successful set-ups can range from a standard 55-litre aquarium with a modest box filter costing very little, to a huge 650-litre aquarium with elaborate trickle filtration, carbon dioxide injection and computer operated lighting systems. Some hobbyists believe that the more expensive the life support system is, the better their success will be. However, all aquariums despite how simple or how specialised, share the same principles for maintaining rainbowfishes successfully.
When choosing an aquarium the largest size one can afford is usually recommended. However, any size aquarium can be successfully maintained, although aquariums smaller than 55 litres are not worth considering. The problem with small aquariums is that the environment can degrade so rapidly that the hobbyist is unable to solve the problem in time to save the inhabitants. The small 55-litre aquarium is often the most popular size with beginning hobbyists because of its moderately low price. However, problems start when they assume that this size aquarium can do more than is realistically possible.
Rainbowfishes are mid-water to surface swimming fish and require sufficient space to swim. It is obvious, therefore, that the shape of the aquarium in which rainbowfishes are kept is of great importance to them. In a small aquarium, they will feel stressed, resulting in disease problems. The surface area of an aquarium is more important than depth. The depth of the aquarium is of no importance, except that it should never be so shallow nor so deep that the aquatic plants fail to grow properly. An aquarium depth for rainbowfishes may be anything from 30 cm to 60 cm, in proportion to its superficies. Aquarium width should be at least 45 cm, particularly for the larger species.
The all-important factor in maintaining rainbowfishes in captivity is water quality. Water quality is important to rainbowfishes as air quality is to you and me. Every particle of waste matter in the aquarium will affect the health of your rainbowfishes, and determines not only how well they will live and grow, but also whether or not they survive. In captivity some water quality factors are more important such as nitrogenous waste levels, dissolved oxygen, pH and temperature. Others, such as alkalinity, hardness, and clarity have some affect, but usually are not significant. Each water quality factor interacts with and influences other parameters, sometimes in complex ways. What may be harmful and cause mortalities in one situation can be harmless in another. Regular testing of your aquarium water and your tap water is important and it should allow you to detect and correct problems before your fish are adversely affected. Therefore, knowledge of water testing procedures and interpretation of the results are important for the successful maintenance of rainbowfishes in captivity.
The first consideration is the availability of a good quality water supply to fill the aquarium. The most common source is town water. Rainwater drawn from a well-established water-tank can be used. However, rainwater is not pure water because it has gases and a range of other particles from the atmosphere dissolved in it, which may include carbon dioxide, oxygen, nitrogen oxides, sulphur dioxide, dust, pollens, bacteria and numerous other compounds. This difference varies with location and proximity to oceans, industry, cities and other contributors. Using rainwater in the aquarium can have a number of benefits by providing a much more natural source of water for your rainbowfishes. However, rainwater should not be used exclusively. Rainwater contains none of the essential trace elements that fish need, and also have no buffering capacity to stabilise the pH. It can however, be mixed with a certain percentage of tapwater. It is possible to produce various water conditions in this manner such as lowering the water hardness or pH of your normal tapwater. Surface water from a natural stream or pond is not recommended as it may contain contaminants, diseases, pests or parasites, any of which may harm the aquarium's ecosystem.
Most aquarists will fill their aquarium with city water drawn from the household tap. However, this water has usually been subjected to many changes. If the changes are within the parameters that the fish can adjust to, then suitable conditions can usually be established. The domestic water supply of most cities and towns if suitable for human consumption will generally be suitable for use in the aquarium.
Nonetheless, municipal water supplies are typically treated with chlorine compounds to control bacteria and make it suitable for drinking. If used for fish keeping, then these compounds must be removed or neutralised with chemicals designed for that purpose. One week of continuous aeration will dechlorinate most town water supplies if the chlorine source is liquid or gaseous chlorine. However, many municipal water supply authorities have switched from using chlorine to chloramine. Chloramine is a compound formed by mixing ammonia and chlorine in water. Chloramine is very stable and can not be easily driven off, even by heavy aeration. Chloramine is very toxic and high levels can cause all rainbowfishes to die within 24 hours. The actual toxicity will depend on the individual fish, water temperature, and dissolved organic levels in the aquarium water. Most rainbowfishes will exhibit serious signs of stress or die at levels above 0.01 mg/L. Some species are particularly sensitive and will die with even the slightest amount in their water.
It is worthwhile to note here that domestic water supplies often change in character, and must be tested regularly from time to time for contaminants, changes in pH values, etc., using aquarium test kits. It is not uncommon for the level of chloramines in municipal supplies to change drastically, for example, due to some local problem and during that period additional conditioner has to be used. Private water supplies are not consistent in their output either, and should be checked on a regular basis.
Many hobbyists fiddle about with various chemicals or compounds trying to maintain what they regard as natural water conditions, but this often causes more problems than it solves. Duplicating the natural water conditions under which rainbowfishes are found in the wild may seem ideal. However, creating natural water conditions in an aquarium is almost impossible.
In order to design a more natural aquarium environment it is essential to have a basic understanding of the biology and ecology of the rainbowfish species in question and especially the environment that the species inhabits. Most rainbowfishes live in the tropical and sub-tropical climates of Australia and New Guinea. They occupy virtually every type of freshwater ecosystem, from slow-flowing, acidic, tannin-stained water in coastal swamps and streams to fast flowing clear-water rainforest streams; riverine habitats and their tributaries; lagoons, billabongs and the waterholes of arid desert country.
A feature of any pristine environment is the huge variety of habitats that are available. Few species of rainbowfishes flourish in bare, barren habitats. Habitat is provided by rocks, logs, fallen branches, aquatic and riparian vegetation. Most rainbowfish are highly social and form schools for some or most of their lives. The behaviour between the sexes also appears to vary with females forming small social groups that stay together while males cruise in search of mating opportunities. Males can also be highly territorial and will engage in spectacular fin-flashing displays during contests with rivals over the acquisition and defence of spawning sites (submerged logs, rocks, vegetation) close to the water's edge. Females move between territories, inspecting males along the way. Males play an active role in courting females and will often swim over to display to passing females. In the wild they tend to spawn amongst stems and roots of marginal aquatic vegetation, especially where the substrate slopes up to the bank.
Most aquarium environments are completely devoid of structure. They are usually featureless, monotonous enclosure with no opportunity for the inhabitants to display any natural behaviour. They bear no resemblance whatsoever to the fishes' natural environment and densities can be up to 100 times greater than those in nature. Simple measures like increasing filter performance, providing dark backgrounds, natural substrate material, submerged structures, such as driftwood, and floating plant cover could improve the aquarium environment. This also leads to lower levels of aggression, better health and improved growth rates. Aquarium-reared rainbowfishes that spend some time in outside ponds improves growth, colour and survival rates substantially. In the pond environment the fish are not only exposed to natural temperature and light fluctuations, they also have access to a range of naturally occurring live foods.
Finally, let me say, that in all the details of the care and keeping of rainbowfishes in captivity, there is no teacher as good as experience. Within a website like this I can only suggest some general guidelines I have acquired from my own experiences. The daily care and attention, on which success so largely depends, I cannot dictate. Each hobbyist will have to discover those conditions suited to his own circumstances by experience and practice. Those who treat an aquarium carelessly or indifferently will soon become tired of it, and cast it away accordingly. Hopefully I have provided enough information for all too successfully undertake the care and keeping of rainbowfishes.
© Copyright Adrian R. Tappin
Updated December, 2008.
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