I got a new betta, a hot-tempered fellow. I wasn't planning on getting one, but when I saw him and how they were treating him I couldn't just walk away. (He was in a cup and had other bettas stacked around him and he was going insane, headbutting and biting the walls of the cup. He couldn't even flare properly because it was too small.)
The problem is, I'm not sure if his injuries are from tail biting, or tail rot. He is a metallic turquoise and red comb tail, and two or three 'combs' in the middle of the end of his caudal fin are missing (though I think one is starting to grow back). Also, in that area, the fins are thin and almost translucent.
I've got him in a 1.2 gallon (5 litres), heated to 26-27 degrees Celsius at the moment (80-82 F), and am doing daily water changes of about 400mL, and twice weekly water changes of 1.25 litres. Nitrites and -ates are 0 ppm. I've had him now for 16 days. The water is conditioned with API betta water conditioner as well as API Stress Coat and a couple of drops of Bettafix for antiseptic purposes. Haven't used aquarium salt yet as am not sure whether it's tail rot and a vet I know scared me by telling me that overusing aquarium salt on bettas makes them more susceptible to dropsy.
Can somebody please have a look at a couple of photos of his caudal fin and tell me if you think it's biting or tail rot? I'm really not sure, because I can't see any black, but then they're thinned out so I don't know ...