When a Bettas gills become inflamed, one or both gills will not close properly. They may or may not look red on the inside, and if in the last stages, they would be gasping for air, unable to breathe properly. A Bettas gills may become inflamed because of bad water conditions, or perhaps from a bacterial infection.
To cure, Isolate any sick Betta with Inflamed Gills, and every third day do a full water change. Every time you change the water, add any sort of bacterial medication you have, I would use either triple sulfur, or tetracycline if available. Get your water tested, if you don’t have a test kit - most LFS (local fish stores) will do it for you.
