This is a banded leporinus. It is also called black-banded leporinus. They are native to the Amazon, but have been introduced to Florida and Hawaii. However, no banded leporinuses have been seen in Hawaii since 2005.
Banded leporinuses eat alage, plants (like the lettuce this one is eating), worms, crustaceans, and other fish.
Banded leporinuses are common aquarium fish, but to fit them in an fish tank, it would have to be one big fish tank. These fish can grow up to a foot long.