My betta fish has popeye in one of his eyes. Does anyone know any good medications, or should I just leave him alone?

Popeye is a bacterial infection, and Tetracycline is a good antibiotic that is available for aquariums at most pet stores. Popeye can be very serious, and he may either lose the eye or die if you don't treat it promptly.

You should test the water to see if water quality is part of why this was contracted. Poor water conditions can cause Popeye. Ammonia and Nitrites above 0 ppm or Nitrates above 80 ppm could cause this.

Another common cause of Popeye is some sort of injury. You can see if the decor would have caused it by running a length of pantyhose along the decor. Anything that causes tears or runs in the pantyhose could also hurt a Betta.

You should also keep an eye on aggression from tank mates as a possibility. Other Bettas, Gouramis, Cichlids, or fish like Yo-Yo Loaches could have injured the eye.