Short-term infection dynamics of the monogenean parasite Ligictaluridus floridanus (Monogenea: Dactylogyridea: Ancyrocephalidae) on channel catfish Ictalurus punctatus (Actinopterygii: Siluriformes: Ictaluridae)

Ligictaluridus floridanus (Mueller, 1936) is a monogenean parasite that affects farmed channel catfish, Ictalurus punctatus (Rafinesque, 1818). No studies, however, have been conducted on this monogenean’s infection dynamics. The aim of this study was to determine the prevalence and mean abundance of L. floridanus on channel catfish fry in a cohabitation experiment. The experiment was performed in triplicate and involved the introduction of five infected fish to a 40-L aquarium that contained 30 naive fish. The trial lasted 29 days and was conducted in a system with a continuous water flow. The percentage of naive fish that were infected increased sharply, from 0% to 100%, between the second and third days after cohabitation. On the subsequent days of the experiment, 100% prevalence was observed, except for days 23 and 26, when it was 66%. The dynamics of infection with L. floridanus showed its main peak five days after cohabitation, exhibiting a dome-shaped function. The left side of the fitted function represented the abrupt increase in parasite abundance in a few days, while the right side depicted its gradual decrease. One would expect that when L. floridanus enters the catfish culture system, it will be able to infect all fish (100% prevalence) within a few days. This would occur primarily in floating cage culture systems, where fish density is usually high. The parasite can disperse rapidly throughout all the gill arches when its abundance exceeds a certain threshold. Further studies on the reproductive patterns of this parasite and the factors affecting its variability are necessary to have a better understanding of its host dynamics and life cycle parameters.