I'm sorry I have no idea what could be wrong. If you post your question in the betta disease and emergencies section of the betta forum with a little bit more info like what size tank he is in, what temperature his water is, feeding schedule etc, then we would be able to help you better. Welcome to the forum.

I have a beta fish who just quit eating. He doesn't seem to be as lively as he used to be either. Anyone know what I can do for him???