What do rainbow fish eat?

Answer 1

Their fish food follows a particular colour scheme of red and orange and yellow and green and blue and indigo and violet.

This can easily be remembered by the ryhme:
richard
of
york
gav
battle
in
vain

:D

Answer 2

Rainbow fish are omnivores and primarily feed on algae, small invertebrates, and plant matter in their natural habitat. In captivity, they can be fed a varied diet including high-quality flake or pellet food, frozen or live foods such as bloodworms, brine shrimp, and plant matter like blanched vegetables.