Why is everyone hating on the goldfish...
SAE and the only reason being a LFS sold me one saying it was an Otto. It gradually became obvious after it was in my tank for about 10 days that it was not an Otto and so I had to catch it and take it back to exchange for an Otto. Have you ever tried to catch one of those things? They are like little superfast torpedos. My tank looked like a tornado had hit it by the time I finally caught the little guy.