I have a 15 year old goldfish that I won at the fair. He was less then an inch when I got him and now he is anywhere from 14-16 inches long and over 3 lbs. He is in an outside tank that has a lot of good algae growing. His tanks are 250 and 300+ gallons. In the winter he is in the smaller tank with a heater and I feed him Goldfish flakes. He had a tank mate that died almost 3 years ago. I want to buy some goldfish (maybe 3) for tank mates for him. They have to be bigger than his mouth. Any ideas?