Life cycle of the fish parasite Gnathia maxillaris (Crustacea: Isopoda: Gnathiidae)

The taxonomic classification of some parasitic isopods of the family Gnathiidae has been revised in the last years. However, their biological cycles have been described only partially or incompletely. Gnathia maxillaris (Montagu, 1804) is one of the most studied species, but certain aspects of its life cycle are still poorly known. A detailed study on the life cycle of G. maxillaris was carried out over several years by sampling larvae from an infestation of large volume aquaria at the Aquarium of Barcelona. At the same time, a system of in vitro cultivation of G. maxillaris was developed, which provided new data to complete the description of its life cycle. Periods of incubation, fertilization, planktonic stages, the attachment site on the fish host and biometric characteristics of larval forms were detailed. The new information may help better control health state of marine fish in aquaculture.