Massive Lernaea cyprinacea infestations damaging the gills of channel catfish polycultured with bighead carp.
During June and July 1998, at least 3 Arkansas fish farms culturing bighead carp (Hypophthalmichthys nobilis) with channel catfish (Ictalurus punctatus) suffered major losses of catfish associated with massive infestations by the crustacean parasite L. cyprinacea. The channel catfish had few adult Lernaea attached to their skin, but there were 8-50 Lernaea copepodids on the surface of each catfish gill filament. The copepodids were found grazing on the gill tissue, and their feeding activity was associated with gill damage including epithelial hyperplasia, telangiectasis and haemorrhage. Bighead carp in the same ponds were reported to have had numerous adult Lernaea on their skin but did not die during the epizootic. It is suggested that the filter-feeding apparatus of the carp may have captured the copepodids, thus preventing heavy infestation of the gill filaments. The loss of catfish in these cases is likely to be due to their polyculture with the bighead carp, a species that provides an excellent host for adult Lernaea.