A carnivore is an animal that predominantly eats meats or other animals. In the fish world, large predatory fish are carnivores, living almost exclusively off other fishes. Some smaller fish are also carnivores, but these often feed from much smaller animals such as crustaceans, worms, and macro-organisms. Carnivorous fish should be fed on meaty foods such as bloodworm, brineshrimp, or daphnia for smaller fish whilst larger fish can be fed on foods such as cockle, mussel, krill, or lancefish. Large, predatory fish actually need surprisingly little food, and are often overfed in the aquarium. A typical predatory fish, perhaps around 30cm in length, should be fed every other day, or even once every three days. Being a larger fish, they have a longer digestive tract, and can therefore spend a longer time extracting all the useful elements of the food they eat.