Wasn't meaning he shouldn't be in a big tank but a long tank rather then a square tank would be best, any standard 45,55 comon 75 are all 4' and considered small tanks to me but would be good for a couple years im sure.and 3' is at max size in the wild good luck getting him any where close to that size.i mean most ppl have a fish for 1-3 years befor passing them on or they die from aquarium diet/life,being that he is 12" allready I would say he might just might dbl in size with in the next 3 years