Occurrence of a Monogenean Gill Parasite Pseudorhabdosynochus epinepheli on Red Spotted Grouper Epinephelus akaara and Its Experimental Treatment by Hydrogen Peroxide Bathing

Abstract

Since 1997, infection of a monogenean gill parasite Pseudorhabdosynochus epinepheli has been occurring in red spotted grouper Epinephelus akaara at the Kagawa Prefectural Sea-Farming Center, Japan. The efficacy of hydrogen peroxide (H₂O₂) bathing was examined in vivo. Bathing in a 700 ppm H₂O₂ solution for 45 min at 10 or 15°C, or for 15 min at 20 or 25°C, with infected fish of 230-2100 g in body weight, resulted in 100% mortality of P. epinepheli on the gills. Mortality occurred in fish (550-1730 g) bathed for 30 min or longer at 25°C, but not in fish bathed for at least 60 min at 10, 15 or 20°C. Results indicate that chemotherapy with H₂O₂ has a high potential as an effective treatment for P. epinepheli infection in red spotted grouper.