I would say keep the water clean and a pinch of aquarium salt. . . if it's only a tiny ripped then it should grow back w/o any problems. But keep a close eye on it. . . . to see if it gets worse.
When i got him the end of his tail was clear as if it has happend before, Just wondering if he ripps it him self, I have 5 Platies in with him but they dont bother with him.
Just thought of that song I used to sing in primary school 'My eyes are dim, I cannot see, I have not brought my specs with me' Sorry just had to share that with you