If you have a cycled QT, you should move the fish there and lower the salinity towards 16 ppt. It will help reduce the chances of secondary infection and reduce energy consumption of the fish while trying to maintain osmotic balance with a large open wound. I would also suggest adding either Kents Protech Marine or Seachems Stressguard. Both contain a protein binding agent that will help the fish heal faster.
If you do not have a QT, watch the fish carefully for signs of infection and still use the above additives, just watch the skimmer output. Make sure you soak the foods in a liquid marine vitamin (Zoe, Zoecon, Selcon) and be very careful of water quality. I would proactively step up the water changes to twice a week in the interim to help keep DOC
down and the potential for secondary infection at bay.