I have recently acquired a halmoon male betta who insists on chewing
his tail. There are some areas of the tail that appear to have
finrot, and some injured from chewing. His past owner and I both have
witness him chewing.

I am currently in the process of fixing the finrot, but this has been
done in the past by his original owner and the chewing still persists
in the absence of finrot.

My question is, is there a way to stop him chewing?! It would be nice
to able to see his tail grow back, even if it's not the same as it
was.

Thanks.