Fish-disease
Guides
Lernaea
anchor worms
Lernaea is a genus of parasitic copepod crustaceans commonly called anchor worms, exclusively parasitic on freshwater fishes. Females burrow into fish flesh and transform into unsegmented, wormlike forms with egg sacs visible externally, while males are free-swimming and short-lived. The genus is widely distributed globally and causes significant disease in aquaculture and wild fish populations. Multiple species exist, with Lernaea cyprinacea being the most studied and economically important.
Lernaea cyprinacea
anchor worm, fish louse
Lernaea cyprinacea is a parasitic copepod commonly known as the anchor worm, a significant pest in freshwater aquaculture worldwide. Native to Eurasia, it has been introduced to multiple continents including North America and South America. The species exhibits sexual dimorphism with females becoming permanently attached to fish hosts while males are free-living and short-lived. It causes substantial economic damage through direct parasitism, reduced fish growth, and secondary infections.