This is because tuna eats other fish. Any animal that eats other animals is called a carnivore.
If, when other fish are in the same environment as piranhas, the other fish are eaten, then piranhas are a type of fish that eats other fish. your welcome
There called betta fish
it eats other fish
An animal that eats fish is called a piscivore. Some animals, like bears or alligators, only eat some fish, and are therefor partially piscivorous. Other animals live exclusively on fish, like seals, and are completely piscivorous.
Seals and any other big animal eats cow fish.
Other fish.
smew
Grouper and other Lion Fish.
Other fish, birds and bears
other fish
Cleaner fish by Jay