I went on vacation recently and left my tanks in the care of a friend. He absolutely neglected them, only feeding them a handful of times and not doing their routine water change as I asked. Their fins are now pretty trashed and they're skinny, the poor dears. They've colored up wonderfully after I overhauled their tank and added fresh, warm water with a little bit of stress coat. The cycle is intact and the water parameters are fine. I was thinking of adding some aquarium salt as well. Any further advice, guys?