i've had jacks grow considerably faster then my GT's (past and present).
alot of factors may determine the growth of "your" fish.
1. Quality of fish. (on a genetic level, but know one would know this unless you were the breeder).
2. Food. (quality, quantity, and is this filling you particular fish needs).
3. Water quality. (is the fish living if feces filled water)
4. Room to run. (or space for activity)
5. Pecking order. (meaning where a certain fish falls in line, because fish that are lower on the totem pole, seem to get harassed more. also get less food. and are stressed considerably more then others higher up, and get "picked on" by most, if not all higher ranking fish).
taking this from past and present experiences. so, use it as you will. my "experiences" might be different then many others.
