Shark Tale (2004) on Netflix

This mafia movie, set in the world of saltwater fish, is the story of what happens when the son of the shark boss(De Niro) of a fish crime family is killed by a dropped anchor, and a bottom-feeder named Oscar (Smith) is found at the scene of the crime. Hoping to win favor with the enemies of the ganglord, the fast-talking hustler poses as the killer known as the "sharkslayer", but soon learns it's a dangerous game in a world where the big fish generally eat the little fish...