Help...So yesterday i got some platies from petco and all but one seem to be doing great. they are zipping round the tank and having fun but one is just chilling by the heater up against the surface of the tank? he? just stays there he is breathing and his fins wiggle bu he won't move unless i go to like adjust the heater. then he only moves to the bottom of the heater so i can't bump him, i tried to see if maybe he was hungry cause the others come to the top like he is if they want food I've noticed but he didn't want anything. he won't even move if the other fish come over to say hello. Idk about you guys but imo a fish that doesn't socialize with his buddies and sits alone at the top of a tank by the heater is a fish with problems what do you think? and yesterday day when i put them in he was fine and zipping around like the rest are today