I have had quite a few snakeheads, and have just recently sorted out my friends bleheri it was so badly damaged it could just about swim to the surface to get air. I put it in a quarantine tank with some Methylene Blue (I know this is out of the ark but my father and I have used it for years on open wounds on fish and it has never let me down) the fish made a full recovery in 3 weeks and is back from the dead. But just remember Methylene Blue will interfere with the normal biological processes of nitrifying filter bacteria. Methylene Blue can also interfere with normal plant growth. But it works well on snakheads have used it loads of times and it realy cleans them up.Add 1 teaspoon of 2.303% Methylene Blue per 10 gallons of water.If its the fins you should be ok if boddy bo the Methylene Blue

When you say red line you are talking about a red snakhead micropeltes if it is thats your man soon to be a killer