My Sammy, HM just recently had a scale pop off, and in about 3-5 days, I saw healing, and with fin damage, about a week, with adequate water change, and AQ salt, but in my HM's case, I did only clean water, and no AQ salt, he is a biter, and he has long fins, so he goes for the tail as soon as it starts growing back..well, we'll see this time, but again, as long as the water is clean there is no chance of rot.
Fishie stopped biting his tail a few weeks ago, but it's taking forever for it to grow back! I use stress coat, but I just started seeing a tiny bit of growth last week, and there's a little more this week, but nowhere near being all the way back. His rays look like they're growing in weird directions in the new growth, too. Is that abnormal or will they straighten out as his tail continues to grow in?
Meanwhile, I saw a tear in Lila's tail one day, and the next day it was healed already.
@Broncosfan, my Sammy looks just like that..yes, it grows back, and stress coat is great for it, but if your fishy is a biter, then it will keep happening, and it takes a while for a lot of growth, but you will start to see a little here and there.