The Fish is both: a natural type of the food and a species of the animals. The fishes are based on the goldfish and are food to carnivores. Snowbert, Pauline and Seamus are the only characters who eat fish.
In different regions, the fish seem to be different. The fishes in Africa are based on African cichclids. The fishes in The North Pole are based on Arctic sardines. The fishes in The North America are based on salmon.