When I had red hooks , I kept them in a school of 5 and they swam all over the tank . They did grow quickly(from a quarter size to baseball size in about 5 months!) in my 55g and then 125g,they are alot of fun to watch !
I don't think mine have grown much. I got them around 2.5-3". They are around 4" now. Its been ~5 months now. They would probably be growing faster if they got more food, but they're being outcompeted by the cichlids.