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Temperature tolerance among rainbowfishes is similar to that for water chemistry. In their natural environment they are exposed to temperatures that vary considerably. Temperature levels are related to the volume and depth of the body of water, flow rate, altitude, seasonal weather conditions, whether exposed to full sunlight or in shaded rainforest streams. The overall range has been reported from a low of 5 degrees to a high of 36 degrees Celsius, and even higher in a small, shallow body of water exposed to full sunlight. These temperatures are natural conditions that rainbowfishes have to be able to withstand to survive, but are not recommended for aquarium keeping. Higher temperatures increase the metabolic rate and oxygen requirements of the fish, while at the same time the water's oxygen content will decrease as the temperature rises. Therefore, a temperature range of 20 to 24 degrees Celsius is suggested for the care of rainbowfishes in captivity.

Rainbowfishes occupy the midwater to surface area of the aquarium and require some open space for swimming. Therefore, the surface area of an aquarium is more important than depth. Rainbowfishes will show their best colors when maintained in a well-planted, partly shaded aquarium. Such an aquarium, tastefully decorated with river stones and driftwood will make a very attractive display. Aquatic plants not only provide suitable habitat and spawning areas for rainbowfishes but will also assists the biological balance in your aquarium. Rainbowfishes are schooling fishes and will be much happier when kept in small groups. Males display to each other by extending their dorsal and anal fins while at the same time intensifying their coloration. This is often accompanied by a side-slapping action while swimming together side by side throughout the aquarium. Extended fin and color intensity is also undertaken by the male when displaying to a female.

Feeding rainbowfishes shouldn't present any problems as they will accept all foods with equal enthusiasm. They can be maintained on a diet consisting totally of prepared foods such as flakes, pellets and granular formulations. However, they will appreciate some live or frozen foods such as bloodworms, mosquito larvae and daphnia etc. Live foods are not necessary but if you have access to them then this is by far the best food that you can feed to your fishes. Rainbowfishes are omnivorous and can digest both animal and vegetable material. In their natural environment they can be seen around sub-surface aquatic vegetation feeding on a variety of terrestrial insects, small aquatic crustaceans, insect larvae, worms, aquatic plant material, pollens, seeds, detritus and basically anything else that will fit into their mouths. Scientific data from stomach content analyses in wild populations can be helpful in selecting the right type of diet for your fishes. However, it is unlikely that you will be able to match that diet in captivity. The best way to ensure your rainbowfishes are getting a well-balanced diet is to feed them as wide a variety of food as possible. With proper feeding and aquarium management, most rainbowfishes will have the opportunity to live a longer life in captivity than they would in the wild. With some species this can be as long as 10 years.

Breeding Rainbowfishes

Breeding rainbowfishes in captivity is relatively simple and can be achieved by maintaining them in an appropriate environment. Fortunately, they are very adaptive and will breed in a wide variety of water conditions. To breed rainbowfish you need to give them an aquarium on their own with a water temperature above 22¡C. Water hardness and pH are not a major factor providing extremes are avoided. However, for at least two weeks before attempting to breed your rainbowfishes, you should feed them with the best food you have available. Commercial flake and pellet feeds will be suitable for most species, although they will all benefit from the addition of live or frozen foods. Feed at least twice a day but make sure you don't overfeed. Also to increase your success try separating the males from the females during this two week period. Choose your breeders and place them in their breeding aquarium. By far the best combination for breeding that I have found is 3 males and 2 or more females. With 2 males one will dominate the other and in effect prevent him from breeding. One male on his own will cause undue pressure on the female/s. Three, on the other hand will spread the aggression, both on the other males and the females. Group spawning with multiple males and females is more natural. Also, this method should provide you with more eggs. Of course, if you have only a pair, then there is nothing else you can do.

You must also know your fish and be able to pick males and females. Generally speaking, rainbowfish can be sexed by the color and finnage of the fish. Males are generally more colorful and have extended finnage, while females are pale by comparison and have smaller or more rounded appearance in the fins. In some species, males change color during the spawning ritual. These physical changes make it relatively easy to identify sexually mature males. If you are unable to sex your fish, then have someone with more experience do it for you.

Rainbowfishes will readily spawn in a normal community aquarium. However, in most cases the eggs or fry will be eaten. By far the best way to successfully spawn and raise the fry is to use a basically bare aquarium and provide them with spawning mops. Spawning mops can be easily made from acrylic woollen thread cut into lengths of 30 cm and tied together in the middle. The mops can be attached to a piece of styrene foam and floated in the water or alternatively, just drop the bundle of loose thread into the aquarium. You then begin inspecting the mops each day, preferably twice a day, morning and night as rainbowfishes are notorious egg-eaters. If you find eggs in the mop then you can either exchange the mop for a new one or hand pick the eggs for hatching separately. Fertile rainbowfish eggs are very firm and can be removed from the mops with your fingers. If you exchange mops, then you can just place the mops into the raising aquarium for hatching. If on the other hand you decide to pick the eggs from the mops then you will need hatching containers. These can be any sort of clean plastic containers. You can add some fungus inhibitor to the water to be on the safe side. Developing embryos display prominent eyespots and this is usually refer to as the eggs being "eyed-up". Infertile eggs become soft and white. Incubation time for most rainbowfishes is around 6 to 9 days at 25 degrees Celsius.

All you have to do now is to watch and wait. If you chose the mop-exchange method, all you have to do is scan the surface of the water each day to see if any have hatched. If on the other hand, you picked the eggs then you need to collect the hatching fry from the containers and place them in their raising aquarium. Do this with reasonable care and make sure the water conditions of the hatching container and the raising aquarium do not differ too greatly. After hatching the fry will remain attached to the spawning medium for about another 12 hours until their swim bladder inflates. They then swim in the upper 1 cm water layer where they start looking for food. They have the appearance of small clear slivers of glass, and should be fed immediately. The fry have only a small yolk sac and to ensure maximum survival, require feeding within a few hours of hatching.

There are a host of finely powdered dry fry foods available on the market. One of the best ones that I have found is OSI microfood, just use it dry and sprinkle it over the surface of the water. You can use one of the liquid preparations, but I find that liquid foods sinks rather quickly and rainbowfishes need their food on the surface or just below. However, a few drops wouldn't hurt and it gives them something different in their diet. Once you get them past a couple of days you can start feeding them newly hatched brine shrimp or micro worms. Most species will also benefit from a growth of algae in the rearing container or the addition of small amounts of green water (phytoplankton).

Remember that the fry have probably hatched over a period of days and when you change from a small food to a larger one, keep feeding the smaller food until you are sure that all the fry are eating the larger one. If you have a batch that differ greatly in size (you will often find that the smaller ones are females), you may find that you have to feed three different size foods if you wish to raise all the fry. Just a small tip here, keep your fish foods in a refrigerator after opening, they last longer. The continued growth and development of the fry will vary depending on species, temperature, water quality and feeding regimes.

Conclusion

Rainbowfishes are one of the easiest freshwater fishes to keep and breed in an aquarium. They possess all the attributes we look for in aquarium fishes: beautiful colors, hardy, peaceful disposition, and they won't destroy your plants or rearrange your aquascaping. They come in a variety of colors and sizes and will make a delightful addition to your home aquarium. They get along fine with each other, small to medium sized cichlids, livebearers, anabatoids, characins, catfishes, and a host of other tropical fishes.

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