I think ollys idea sounds brilliant. Sure it may have some flaws in terms of other stimuli/conditions affecting your results, but this can all be talked about in your analysis at the end, and about "how youd do it better next time". The teachers/judges will love that you can critique your work and make suggestions about furthering your study, because doing so is so vital to scientific experiment in general.
Had a random idea to, not sure if this would even work, but would be interesting. The cave tetra manouevers itself through the water by echolocation (i think, you might want to check this ). What would be facinating to have shown is whether the cave tetras ability to sense structure through sound is better than say a normal fishes ability through sight. What im thinking is if perhaps you had a maze set out and did multiple (and i mean heaps) of runs where fishy was placed at one end, and something smelly at the other, who would get to the end first? Cave tetra or other? Again its heavily flawed in that your dealing with different types of fish, and so naturally there is going to be some difference in mental capabilitys (ability to learn, memory capability etc) but anything you wish you could improve but didnt have time/money/foresight for can all go in the writeup at the end.
