I'm doing a project on feeding goldfish for my science project. Tell me what you think of these diets:
TANK ONE
Goldfish flakes everyday.
TANK TWO
Goldfish flakes every three days
TANK THREE
Flakes, frozen brine shrimp, peas, lettuce
TANK FOUR
peas, lettuce, cucumber (veggie things etc.)

what do you think sounds best? worst? tell me please
(btw, I am experimenting with red cap oranda goldfish)

How long is your science project for?

Usually a science project has a "hypothesis"--what would yours be? And like lcwinne said, how long is it for?

And if the hypothesis has anything to do with the health and vigor of the fish, it bothers me a bit that you would be experimenting with living things.

But if it is a short time it would probably be ok. Goldfish are mainly protein eaters and a diet of just veggies for an extended time would not be good. Of course you would need four tanks with the same conditions (filters, etc.).

My son did a science experiment with radish seeds--some had better soil or fertilizer and it made a visable difference--the ones that had better soil got bigger fast. His hypothesis was that improved conditions would create an improved radish.

If the type of goldfish feed is changed, then the fish will have different brightness, health, and activeness, because of the changed feed.
that the hypothesis. And I *really* am not trying to kill them-i'm just wondering what diet is best for them
I've already started the project and its going for aobut 3 weeks. One fish (very sadly) died (it was in the tank with the varied diet)...but I think it had a disease since it had some discoloration and a lump on its side.

Is 3 weeks enough to show any changes, and some changes are genetic.

Yes, and actually it only is going for 2 weeks now. I have noticed a very large drop in the activity of the fish on the vetgitarian diet, and I fear that their health will suffer greatly if they are not taken off that diet very soon.

what is the volume of water that they are housed in and the filter? That makes the first difference, before food. A goldfish under stress no food can make the difference.