Wow, that cost a lot for just plain old Tetris
Turns out, you have to play and unlock achievements to be able to use those fish. Something that they don't mention when you buy them or the tank backgrounds. Now, I can see unlocking FREE content to make it better, but if you're going to make me pay for it, let me use it right away. So while I'll admit I'm an idiot for spending real money to buy digital fish, I really do think what XBL is doing here is just plain evil. It's bad enough to know you just bought digital fish, but to make it so we can't see those fish - that's kicking a man when he's down.