Keeping Rainbow fish

If you want to keep rainbow fish, there are many things to take into consideration. If you want to keep healthy and good looking rainbow fish, you must provide them with an environment and diet akin to what they are used to from the wild. Keeping rainbow fish in an unsuitable environment and giving them “normal flake food” will almost always lead to ulcers and premature death.

Keeping rainbow fish on a suitable diet

Rainbow fish will eat practically anything you give them, but that doesn’t mean that it’s healthy for them. A key element in keeping Rainbow fish healthy is therefore to provide them with a diet that is similar to what they would eat in the wild. Wild rainbow fish feed mainly on algae and other plants, but also eat aquatic insects, terrestrial insects, tadpoles, crustaceans and really small fish. A majority of their diet is however always made up by algae.

When aquarists place rainbow fish in their aquariums, they often give them ordinary flake food with a low algae content. Even a really good high-quality flake food is however normally a bad choice for rainbow fish, because the composition of most “general” flake foods is tailored for omnivore fish that eat more meaty food and less algae food. A diet rich in protein and low in fiber is not healthy for rainbow fish and will increase the risk of various health problems.

Many people give their rainbow fish a protein rich, or even fatty, diet since this increases the growth rate. An increased growth rate is however not the same thing as a thriving fish. The fish may seem happy and healthy, but this type of diet will greatly increase the risk of future health problems.

Examples of suitable food types

If you can stand having some natural algae growing in your aquarium, this is naturally the best food source for your rainbow fish. Not only will the fish receive nutrients from the algae; they will also be able to carry out their natural foraging behavior. Algae or algae-based food should be ideally combined with vegetables. You can for instance give your rainbow fish boiled peas, pumpkin and zucchini.

Staying away from all sorts of meaty food is however not a good idea. As mentioned above, wild rainbow fish feed on insects, crustaceans, small fish, etcetera. This means that they need a certain amount of meaty foods in the aquarium as well. The meaty food should however never make up more than 35-40% of the diet, and fatty food should be avoided altogether. You can for instance give your rainbow fish mosquito larvae, fruit flies and fish fillets. Stay away from food types that the rainbow fish could never obtain in the wild, such as beef heart.

Seasonal variations

In the wild, most rainbow fishes live in regions subjected to wet and dry seasons. When the dry seasons ends and the wet season begins, the animal life will more or less explode and the water will be teeming with insects, crustaceans, tadpoles, fish fry etcetera. Wild rainbow fish is therefore used to consuming plenty of protein rich food during the wet season and a low amount of protein rich food during the dry season. Regardless of time of year, their diet is however always made up by a large portion of algae. Mimicking this type of seasonal variations may therefore be beneficial for rainbow fish, especially if you want to induce breeding since they are known to breed at the onset of the rainy season. More research is needed before we can know whether or not seasonal variations are important for the health of captive specimens.

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