I lent a wild type & a golden to someone - similar sized juveniles. After a couple of months I was rung to collect the golden back....all 4 legs gone, one gill & a full half the tail - what an awfully sad sight. One of the legs was particularly unpleasant, as there was bone protruding & it looked a very 'angry' wound. I added loads of oak leaves (for the tannins), & within 9 - 10 months he is almost indistinguishable from others his size - even the muscle within the tail, as well as the fin area, regenerated fully.
Not something I would have planned, obviously, but a stunning demo. of the powers of rejuvenation.
He is now back in a mixed tank with 3 others (one golden & two wild), & I have had no other problems.
Wonderful creatures!
H