This work presents a promising method for automatic, non-contact, detection and counting of salmon lice infested on salmon in an aquacultural farm setting. The method uses fluorescence from chitin in the visual part of spectrum to enhance the contrast between fish skin and salmon lice, and show that the fluorescence is even strong enough to give a real-time view of the digestive and reproduction system in live lice without use of staining dyes. The wavelengths used are compatible with an underwater measurement system.