Ours eat just about anything they can fit in their mouths and if its too big they pick it apart. Mainly though they eat frozen brine shrimp, bloodworms, krill, guppies and goldfish. They have grown so fast already. They were about the size of a quarter when we got them 3/31/08 and they are about 4" already. We call them hoover, eureka, bissell, dirtdevil or any other vaccuum name that comes to mind....lol