If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Drop your hook when you see fishes pass by. Hook as many fish as you can before time runs out, but catching fishes will increase your time. However, you need to avoid the junk people have thrown under water. These things will take your time away. Also, watch out for the thunder cloud.
This game is played with the mouse only.