I agree with that, i've used melafix before its okay, but honestly, good old salt is great. and the tail should grow back, but in some cases may not grow back the same shape it was, depending on how bad the injury, my female flowerhorns tail was practically munched till the base really bad, its grown back took a few months for it to look like a proper tail though, but its fully recovered now, just doesnt look how it used to.
Good luck, salt is good lol