Press X to swim up, and the Arrow Keys to move left and right. Hold the Down Arrow to gobble up small fish when you are on top of them. Eating fish will add to your score and fill up your ink attack special move. When it is full, press Z to unleash it!
Some fish are dangerous and need to be avoided. Swim to the top of the surface to move through the levels. But be careful… if you run out of lives you have to start back at level one!