How do you move te big rocks with things under them like the fish in the..

Small boulders, like the one on the fish, require you to get the Bill Drill move first. You'll get it later on in the game.

Go to "Glitter Gulch Mine"(world #2)to learn "Bill Drill".Well,Bill Drill the rock,and take him to the water to get extra air,and learn how to swim
Faster!

You nedd the move called Bill Drill. You get it in Glitter Gulch Mine. To use the move, jump and hold Z.

If u learned te bill drill move in Glitter Gulch then u go next to the rock press (A) jump onto it press (A) again then hold down (Z) and u get the fish

Must go to the mine Area and then you go Dow to the stumps that should be on your left you will see a metal tunnel thing with a red light off in the distance you get on those stumps and make it to the top then the mole will teach you the move a.k.a just hold z button longer but it does not work until you speak with him after you learn the drill skill you go back to level one and go to where the fish is located and get on top of the rock and then press z and hold then your bird will kazooie will start drilling after the rock has been drilled the parts of rocks will disappear and then you go speak with the fish and the you take it to the water and it will teach you how to swim faster all you need to do to swim faster is press a + b at the same time I hope this help you.