The recent trials for lernaeosis control were directed to the using of natural substances which are more safe and effective than organophosphate pesticides. Both crude colophony and its steamed oil fraction were tested for lernaeosis control in C. carpio fingerlings. The median lethal concentrations (LC50) of crude colophony (crude resin) and its steamed oil fraction were tested. It was 46.7ppm for the crude colophony while up to 100 ppm of steamed oil caused no deaths among C. carpio fingerlings. Direct and indirect bath exposure to 5 ppm of steamed oil fraction for 24 hrs, completely eliminated the lernaea from the infected C. carpio fingerlings post 96 hrs from bath exposure. On the other hand, the direct bath exposure to 5 ppm of crude colophony for 24hrs completely eliminated the lernaea from the infected fish post 120hrs from bath treatment.