Ruffin the Fish

Ruffin is a little fish with a dark past. When he was young, he was captured by an evil scientist, who used him for his experiments. Ruffin was injected with a toxin. One day Ruffin managed to escape and returned home. But now he is somehow different. His mutation, caused by the toxins from his past, made him suffer from monstrous hunger.
Ruffin can eat all the fish which are smaller than him and must hide from the bigger monsters.