Common Monogenean Parasites of Fishes (FA28/FA033)

Figure 3. A gyrodactylid from the skin of a goldfish Carassius auratus. The arrows point to the anchors of embryos. Note the lack of eyespots (left, 100x magnification; right, 40x magnification).Monogeneans are a class of parasitic flatworms that are commonly found on fishes and lower aquatic invertebrates. Most monogeneans are browsers that move about freely on the fish’s body surface feeding on mucus and epithelial cells of the skin and gills; however, a few adult monogeneans will remain permanently attached to a single site on the host. Some monogenean species invade the rectal cavity, ureter, body cavity, and even the blood vascular system. Between 4,000 and 5,000 species of monogeneans have been described. They are found on fishes in fresh and salt water and in a wide range of water temperatures. This 10-page fact sheet was written by Peggy Reed, Ruth Francis-Floyd, and RuthEllen Klinger, and published by the UF Department of Fisheries and Aquatic Sciences, June 2012.