So I've had my betta since May 4th and its currently May 25th. He is a dumbo halfmoon. When I got him his back fin appeared just fine (actually they all appeared great to me). I've attached a picture from when I got him. Now his back fin appears either clamped on the top or possibly missing with a red area where it seems it might be clamped? I've attached pictures from that as well. His tail is looking worse than it did when I got him. I do weekly 20-30% water changes and he is in a filtered tank with a heater. Can anyone help diagnose him and guide me in how to help him? He isn't acting different or swimming any differently. He's eating just fine. I noticed last week that he was flaring at what I'm assuming was his reflection because he is a hexagonal tank which had great reviews and other betta owners stated they didn't have this issue. I do plan on getting a different tank this weekend. I've been doing everything I can for the time being to prevent any glare in the tank so he can't see his reflection as I felt he may be getting stressed out from that. So breakdown of pictures: -Here is one just regular pic with no drawing on it. This is his current state. -Purple drawing: This is what I'm referring to that I think may be a clamped fin and you can see the redish/pink looking area. -Red drawing: Is this fin rot? Or is this normal looking? -Orange drawing: His fins have always been a little uneven in these areas. But not quite as uneven as now maybe. Is this normal? -In the cup: This is from the day I got him for reference. Thank you for any assistance you can provide! I'm trying to be the best betta fish owner I can be!