In Vitro and In Vivo Antiparasitic Efficacy of Praziquantel against Monogenean Ligictaluridus floridanus in Channel Catfish (Ictalurus punctatus)

Abstract

Gill monogenean Ligictaluridus floridanus is the most common parasite on cultured channel catfish (Ictalurus punctatus) in Tamaulipas, Mexico, affecting fish growth and possibly promoting secondary infections. In aquaculture, treatments against fish parasites include the use of chemotherapeutic agents to control and prevent diseases. The aim of this study was to evaluate the in vitro and in vivo efficacy of praziquantel baths against L. floridanus on I. punctatus. In vitro experiments evaluated  L. floridanus attached and unattached to gills; for this, parasites were exposed to 2, 5, and 10 mg L^-1 of praziquantel in distilled or fish aquarium water, and saline solution. For the in vivo experiments, channel catfish infected with L. floridanus were separated into two groups; fish of the treatment group received three 90-min baths with praziquantel (10 mg L^-1) at 72 h intervals. Parasite prevalence, mean intensity, and abundance were assessed by gill examination. In vitro results of the praziquantel in saline and distilled water showed that it reduced the time needed for parasite elimination (p<0.05); whereas no difference was observed in the aquarium water, as compared with the control group. In vivo results showed a reduction in the prevalence and mean intensity of the parasite, and a significant reduction (p<0.05) in the parasite abundance in the treated fish. Consequently, the present study shows that praziquantel is an effective chemotherapeutant against the ectoparasite L. floridanus, significantly reducing its abundance.