Prevalence and spatial distribution of the ectoparasites on the gills of from River Penna flowing through YSR District, Andhra Pradesh, India.

A parasitic survey was performed during July 2017 to February 2018 to emphasize the prevalence and spatial distribution of ectoparasites in from three sampling sites of River Penna flowing through YSR District, Andhra Pradesh by routine parasitological procedures. A total of 238 ectoparasites were obtained from the gills of 70 examined fishes with a prevalence of 77.1%, mean intensity of 4.4 and mean abundance of 3.4 respectively. Three species of ectoparasites i.e., two monogeneans- (n = 119); (n = 90) and one copepod, (n = 29) were obtained from the gills of the host. All the 3 species of gill ectoparasites showed an aggregated distribution pattern (2.92, 2.52 and 2.83). Only, showed a significant positive relationship between the condition factor and parasitic abundance (r = 0.361,  = 0.0021) followed by (r = 0.206,  = 0.086) whereas the parasitic abundance of (r = - 0.213,  = 0.076) showed a weak negative correlation with the relative condition factor of the host. Parasitization was analyzed location wise and fishes collected from Site-I (Mylavaram) were highly infected with both the monogeneans while parasitization with copepods was nil. However, the parasitization of copepods was relatively higher in Site-II (Chennur). There was no influence of host size and host sex on the parasitization and also no specific preference for the sides of the fish host. The monogeneans segregated the niche to prevent resource competition i.e., and were prevalent in gill arches II and I respectively whereas occupied gill arch III. Both the monogeneans showed very a high interspecific association (r = 0.96) with each other but showed a very negligible association with This type of study will help the aquaculturists to implement many advanced management strategies in aquaculture and improve the yield of in the Southern states of India.