I feel so bad, I had ember tetras and they’ve been nipping my betta fins. I’ve had them for 8 months and they were babies when I got them, so I think the nipping started more recently or at least got worse. For awhile I could tell his fins were damaged and removed driftwood, coconut cave, ext. then I saw them nipping at him! 3-4 would do it often, so it definitely got worse. So I brought the embers back to the pet store to find a new home. I just noticed that one of his fins are also basically to the bone and this is new. I bought Indian almond leaves and Capprita bark to release tannins and the medicinal properties, I put it in two days ago and I haven’t seen any tannins in the water yet. I also have snails so I don’t want to change thing to quickly but I want the betta to heal before it gets infected or worse. I boiled two of the leaves and added that to freshwater but no tannins released. He’s in a 10 gallon tank by himself with snails now. Now that the problem is removed, when should improvements be seen? This is a lesson that I’ll never have another fish with a betta, embers are supposed to NOT be fin nippers and I didn’t see it happen for a long long time but poor guy was being tortured by then.