That is a very good question. I don't like adding oil based meds to the tank because I feel it can impede the up take of oxygen by preventing the gills from working at optimum efficiency. They do have some bacteriostatic action but for moderate to serious infections they are similar us putting a spray disinfectant on a cut. They can be useful for minor scrapes etc. but IMO no more so than salt which helps improve gill function and reduce stress. I feel this is an important aspect in the treatment of sick or injured fish. They do smell nice.