My salvinis were eating fine at first and now they have both stopped eating and wont eat or go near each other also my little Geo wont touch a lick of food either what could be causing this all they do is sit at the bottom on there bellys or float near the filter??? Google says that it could be the aggression level in the tank but it has never been a problem for them before so i dont think thats it. what do yall think it could be???