Undermine

Humans are starting another war and its consequences are affecting other creatures too. They have deployed naval mines across the sea that can be very dangerous for fishes and all other marine animals. So the wise turtle (!) tells you that you have to destroy these mines and get rid of them so sea can be safe again. But you start as a clownfish that is not strong enough. So you have to swim across the sea, dodge mines and gather stars to unlock other stronger fishes in store. There are 6 fishes in total and each have its own unique special ability. In order to complete the game, you have to unlock them in order till you reach the final one (shark) that has the ability to destroy mines. After destroying a certain number of mines with shark, you will finish the game and sea will become safe!