How many secret stars are there in super Mario 64?

I think there's only fifteen, but these are the only ones I know. There's one in the room where there's those fish tanks,its in one of those little boxes on the wall ( you'll see what I mean when you see them). There's one in the room where you change characters, Mario Yoshi etc. Jump in the painting of princess peach on the right, and there's a slide that you have to slide down.