Agreed with the above. I keep a group of 15 in a 1300 gallon tank and they eat and eat and eat and grow and grow and grow....... They do beat on the other tankmates, but during feeding time is when other fish get hurt, cuz these guys only have one thing on their mind, no matter who or what gets in their way. Its quite fun to watch the frenzy.
Basically I feed them till they can't anymore, then I feed the other fish.
They are very neat and can get quite large as previous posters have stated. good luck.