I would do this:
1) Add 1 TBS aquarium salt per every 5 gallons of water in the tank.
2) Try to get some Melafix as that is a natural tonic that helps prevent infection and also heals torn fins and wounds. You can get it at walmart even.
3) Keep a close eye on the wound area and if there is any cottony growth you will need to get a fungacide such as Pimafix. You can use the salt, Melafix and Pimafix all at the same time and they work well together.
Both Pimafix and Melafix are by API.
Good luck and please give us an update!