Koi carp eat small fish
Koi is an omnivorous animal and basically eats everything. Except for its own kind, other small fish may not be regarded as koi. Food eaten. In nature, it is a natural order for big fish to eat small fish. Especially when food is in short supply, koi will eat other small fish in order to fill their stomachs. But if there is enough food, koi may still get along well with other small fish.