At least I think that's what it is? The first 2 pictures are from when I got him. The 3rd picture is from March this year. And the last 2 are from today. The length of his tail looks identical from March to now. He acts normal and happy, swimming around all excited and happy to see me. He's quite active, eats fine, attacks his reflection and whatnot. I feel like I've tried EVERYthing to get this fish healthy. I've done Bettafix, Bettarevive, aquarium salt treatment... I got rid of the original plants shown in the pictures, got silk plants, threw those out 2 weeks ago. I'm pulling my hair out at this point. So I decided to get him into a larger filtered tank. I just transferred him from a 3 gallon tank to a 10 gallon a week ago, after an aquarium salt treatment. He made a bubble nest for the first time, so I think he's really enjoying the extra space. I also added some Java Ferns to replace the fake plants. What I want to know is: do you think this is fin rot? Or is it tail-biting? Are the white tips regrowth or further rot? Wahh. Maybe he'll do better in the 10 gallon. I was pretty religious with the water changes in the 3 gallon tank but perhaps I just didn't do enough. I just want your opinions. He acts so healthy. I'd appreciate any tips or thoughts. Thank you!