My Betta had fins like that. A little transprent at the edges and a couple of little holes. There is no blackness or red around the edges. It didn't really seem to get any worse so I didn't treat it. But over the weekend I was really busy so didn't really look at him and when I checked on him Monday 1/4 of his tail was gone! So I did a water change, added salt and started him on BettaFix. I will also lower the temp. I pray this helps.
If your fish's tail is getting worse I would definatly treat and change anything that would be stressing the fish.
Patricia
