Somebody dropped off a 10" chinese hi-fin 'shark' at the store I work at and he has been suffering ever since because even the tanks without heaters maintain a constant temperature of 78 because of all the reptile heat lamps in the area. So I brought him home because the temps are starting to affect his health, I just need to know, if I lower the temps in my 180g to 72 degrees will it be detrimental to my other fish (see my signature) if I keep the temps that low until I can get the shark into his own pond.