A science project is fine and dandy... but unless you compare the lifespan of said fish, you're not going to see the detrimental effects. Sure, a big fish isn't going to grow as quickly in a small tank as it would a big tank. What you didn't consider is that it also isn't going to live as long, healthy, and happy. The fact is, you can get upset, mad, whatever... but none of us will willingly sit back and watch someone recommend a fish that gets too big for the CURRENT TANK, nor will we pass up on informing someone that their fish are too big. I don't care if you plan to get a bigger tank. I plan to win the lottery one day. Doesn't mean it's going to happen.