Are you trying to get us to buy feeder goldfish, lol.
Well, I've heard many stories of people adding feeders to the tank as food. But they don't get eaten and grow and live long happy lives. Also they are very pretty with unique colors and patterns. But I wouldn't recommend you buy one, scottlocks. Firstly, your tanks are too small to raise one. Secondly, you don't have a fish that will eat it.
So I'm confused as to why you are looking into them.