Ectoparasite Prevalences of Grouper Fish (Epinephelus fuscogutatus x Epinephelus polyphekadion) Cultured in Floating Net Cages

Abstract

Monitoring the health of the reared fish in a floating net cage (FNC) is often conducted by examining their ectoparasites. Th is study determine s ectoparasite prevalence s of grouper fish (Epinephelus fuscogutatus x E. polyphekadion ). It was conducted in the waters surrounding Pongok Island, South Bangka Regency. The health examination of both fish and ectoparasites w as carried out by apply ing simple random sampling during three periods, November 2016 (I), February 2017 (II) and May 2017 (III) . H ydro-oceanography surve ys were done every month during th e th ree year s . The grouper checking s (I, II and III) indicated the prevalences of ectoparasites in these periods were 43.3%, 8.8% and 13.5%, respectively. Fish death highly occurred in the period I , and the grouper surviv al rate at harvesting time was only 70% from initial seed stocking of 1 , 500 fish. T he ectoparasite intensit ies during the research periods we re 1.6, 1.6 and 1.5, respectively. This condition implies that every 10 grouper s would potentially be attacked by at least 15-16 ectoparasites. A slow seawater current flow trigger ed the quick uplifting of the ectoparasites from the seafloor. The water condition at the FNC location in 2011 and 201 7 was still under the quality standard. Th e ectoparasites were coming from the surrounding environment of the FNC location . I t is inevitable that the fish culture management should focus on cleansing the ectoparasites attaching on the groupers, dusting the net cage clean, and arranging the harvest pattern on a particular month following the surrounding environmental condition to prevent ectoparasite attacks .