Just to add to what Brian said about them not reaching full size, in the wild they grow to about 12", but in the aquarium 8" is a realistic size for these fish.
no matter what people say, they will flame you that the fish will get too big for any small sized aquarium which in a way i do and dont agree. The fish may never reach full potential of growth during the owners time period. I have 2 right now and thinking of getting 2 more for my 10 gallon. MAYBE one day if they hit 5" *doubtly* I will switch them out but they most likely never will in at least years from now. As for anything they are very SLOW growers...