Its hardy vitality enables it to adapt to any environment. Its pincers will never release prey.
CORPHISH were originally foreign POKéMON that were imported as pets. They eventually turned up in the wild. This POKéMON is very hardy and has greatly increased its population.
CORPHISH catches prey with its sharp claws. It has no likes or dislikes when it comes to food - it will eat anything. This POKéMON has no trouble living in filthy water.
Once it grips prey with its large pincers, it will never let go, no matter what. It is a hardy POKéMON that can thrive in any environment.
It came from overseas. It is a very hardy creature that will quickly proliferate, even in polluted streams.
— Pokédex entries (via PokeAPI)