Click either the red, green, or purple fish. That determines difficulty from (easy) left to right (hard). Move your mouse around to move the fish. Focus on eating as many fish as you can, but stay away from Sharks, Crabs, and Jellyfish. They come from the left side, so stay right.
I have no idea what happened. I tried editing and now it says remixed. I made this game, so it's not a remix. Thanks for playing.