Can some1 help ive just noticed my convict has a small group of white spots on his head they seem too have poped up over night. the only thing ive changed in his tank is i droped the temp down from 26 down too 23 to help with his aggresion also he is the only fish in the tank at the moment. water was 2 3rds changed 4 days ago. does any1 know what is going on ? he seems too act normally anyway if a bit shy. thanks for any genuine answers paul.