Fished several years in Florida with a local guide, he would rub the fin wound on the belly of the offending fish. He said the slime would make the injury less sore and not swell as much... (Course he had 5 beers in him by the time we met in the mornings, so that might have helped too.) I have tried it on salt water cats and it does helps some, but not as much as it helps of freshwater cats...