Identification of ectoparasites in red hybrid tilapia (Oreochromis sp.) cultured in earthen pond

Red hybrid tilapia (Oreochromis sp.) has shown a rapid increase in production from lakes and reservoirs in Malaysia. Currently red hybrid tilapia was recorded as the most common fresh water fish being farmed, where up to 46% was cultured in earthen pond system. Unfortunately, disease infection especially parasite infestation had affected the normal growth and production yield of the farmed fish. The present study was aimed to determine the prevalence, identification and pathological lesions of the ectoparasite present in red hybrid tilapia cultured in earthen pond. In the study, 30 red hybrid tilapias were collected from three different farms within Selangor but only 17 fishes (56.7%) were infested with ectoparasites. The morphology of the ectoparasites was determined based on the light microscopy and the number of ectoparasites observed were counted and tabulated. There was only one ectoparasite species found viz., Dactylogyrus sp. (Monogenea) that has infested the gills region. Histopathology of the gills samples showed hyperplastic changes of the lamellar epithelium and erosion of the lamella. Opisthaptor of Dactylogyrus penetrated deep into the basement of gills membrane where it induced a hyperplastic reaction which subsequently destroyed the secondary lamella. Further study is required to improve the farming of the cultured red hybrid tilapia in earthen ponds to reduce or eliminate ectoparasites infestation