has anyone had this problem? a bala I have has his mouth stuck or grew deformed that way? its open all the time, he cant compete well for food, should I catch him in a net and force it closed? its been like that for 2 months now.
Try seperating it and see if it will eat more. I mean if this fish is deformed then it is also the weakest in the group. If it's by itself then it could eat more