Really need to know the time frame and what you have to do for this project..
Somethings you can do is train oscars to do things, jump for food navigate through obstacle courses etc..
Or you could do something like how much temperature affects growth of fish, breed say 50 guppy fry and try them at various temps in different tanks, or try the same temps but different foods even some cheap ones off trademe and some top of the line ones or special "growth formulas" or brineshrimp etc..