What should i test out with a gold fish?

Okay so far all I have is
Does the tempature of a GoldFish affect the ...

what could be the ... to test out ?
like the heart rate , swimming speed ?

for a science fair project

I've studied animal experiments in psychology and I think you should do an operant conditioning study. You can teach your goldfish to respond to a light in order to recieve food. If you stick a coloured sticker in the tank, everytime the fish touches it, it will recieve food. But make sure the light(eg torch) is on whilst the fish touches the sticker. This will help teach the fish to respond to light signals. If the fish touches the sticker without the light being on, dont give it food. This will mean that the fish will touch the sticker when the light is on and not when there isnt a light signal. This can show how clever the fish can be, and how behaviour is learned.Pyschology is a science afterall, so will be helpful to show signs of intelligence etc.
Make sure you repeat this several times until your fish has grasped this concept, otherwise you may have one very confused fish.
Hope I've helped, let me know how you get on x

Um I need it to be done in 1 day (:

Ah right,um, test times it takes to swim then. You could test it's speed from one end of the tank to the other, then put obstacles in like a bridge, or soemthin to swim through, record results etc, does this help?