Flukes are primarily parasites of gills, skin and the oral cavity, although a few occur internally in nasal cavities, intestine, ovipositor and urinary tract. They are quite small, with the largest being up to 4 millimeters in length, but generally less than 1 to 2 millimeters. Therefore, they are most readily diagnosed with low-power magnification of skin scrapings and gill biopsies. Most flukes are browsers, moving about the body surfaces, and feeding on skin mucus and gill debris. Flukes have a series of hooks that enable them to attach while feeding.

For more information, please read Flukes.