well i have a 55, and when i first bought the tank, i had a 6 inch hippo tang, and a 5 inch naso tang in the tank, they looked soo cool, they seemed so happy too, the naso ended up dying due to a problem that occured in the tan (deprived of oxygen), so i put the blue tang in my parents 6 foot tank, now my parents dont do water changes, or anything, so the water is not in pristene condition, the hippo was in there for about 3 months, and i saw him completely white, and floating upside down, it was once such a fat fish, and you could now see his ribs. so i put him back in my tank, 2 months later, the hlle is gone, the fish is no longer white, the fish is very fat, etc etc, so it may not be the best thing for the fish being in a 4 foot tank, but this fish got nursed back to health in my 55, so i ask you now. whats so horrible about that?