To unlock the Concave Dam lake, just play the game 50 times. To see how many times you've played, just check the memory card icon for the game.

When the title screen comes up hit triangle, X, O, Square, up, down, left, right if u use the code corredtly you will hear a splash then just fish and catch all the fish you want!

At the title screen, press Up(2),Down(2),L1,R1,L1,R1,X,Circle,Start. Then, enter the "Options" screen and press Select to display a "Total Count List" that shows how many game played, line breaks, fish count, and types of fish caught.

To fish at center lake you have to play the game 100 times. You can see how many times you've fished on the total count page.