I was just doing some casual reading online and I came across this story of how C02 cauterizes the wound of an injured fish. It causes the blood vessels to constrict and stop the bleeding. Any carbonated water or soda will work apparently, and its not a big deal to just carry a bottle or two in your boat in case you catch a fish it is bleeding in the mouth or gills. I will definitely be trying this out this summer. The original story link is below.