sounds about right... you might get away with 150 gallons... but if you have the space and the money go with 180 be wary of putting jack dempseys in with oscars... sometimes they dont get along... and make sure the other fish are twice the size of the oscar and that you introduce them all at once... oscars tend to get bullied when theyre juvies... but grow very fast so theyll soon be much larger than the others