I think I have a tail biter on my hands as well, though I can't be sure because I haven't been able to see any real damage on his fins, he has just started to chase his tail occasionally.
I think I saw an incredibly small amount of damage on one fin, but I'm not sure, because his fins are so large they ruffle most of the time. I added a mug to his tank in a panic last night in order to give him a hidey-hole (I was due to purchase a pot with plants attached today, what timing...) but he doesn't seem interested in it.
He always has a piece of IAL in his water, has a potted anubias nana and a dwarf rush planted in the substrate, and gets his regular water changes. I'm panicking a fair bit, and feel like a failure of a fish parent.
Sorry to the OP to hijack your thread somewhat, but aside from changing water, treating with aquarium salt, giving him more stimulation, adding some stress coat instead of regular water conditioner (is this the correct way to go about that?) is there anything I can do? I feel so bad for the little guy, like I've failed him.