Spatial distribution of monogeneans and their prevalence in two freshwater fish species in relation to some physico-chemical parameters of Kenyir Lake,Malaysia

A parasitological investigation was carried out on two freshwater fish species - hampala macrolepidota andhemibargrus nemurus (n = 460) for gill monogeneans from four stations in kenyir lake [station i-kiang river (5°6'49.47 n,102°44'36.60 e); station ii-petang island (4°58'35.65 n,102°47'3.74 e),station hi -ketiar river (5°3'48.38 n,102°34'14.70 e) and station iv -tanjung mentong (4°48'36.54 n,102°45'40.56 e)]. four monogenean parasites were detected viz: bifurcohaptor baungi and cornudiscoides malayensis from the gills of hemibargrus nemurus; dactylogyrus quadribrachiatus and d. macrolepidoti from gills of hampala macrolepidota. their spatial distributions on the host gills are reported. the prevalences of these parasites were correlated to physico-chemical parameters (temperature,dissolved oxygen,ph,ammonia,nitrite,and alkalinity) of the lake water. the results revealed that all the stations were infected,but the highest infestation was in the third station (ketiar river) with 100% prevalence and intensity of 43 individual worms per host. correlation between physico-chemical parameters and parasites prevalence shows statistical significance (p < 0.05),especially between prevalence,mean intensity and total ammonia nitrogen (tan). in conclusion,monogeneans from these two fish species were not randomly distributed but showed site specificity. © universiti malaysia terengganu publisher.