Parasitic copepods infestation on commercially exploited fishes from Kayamkulam backwater, Kerala, India

Parasitic copepods infestation on three species of commercially important fishes belonging to the family Mugilidae (Liza parsia) and Cichlidae (Oreochromis mossambicus and Etroplus suratensis) from Kayamkulam backwater were analysed between February 2015 and January 2017, covering all the three seasons. A total of 2305 fishes were analysed for parasites. Out of these, 299 fishes were infested with different species of parasitic copepods. The analysis revealed the presence of ten species of parasites comprising of Ergasilus parvitergam, Ergasilus sieboldi, Ergasilus sp, Caligus epidemicus, caligus sp, Dermoergasilus hoi, Dermoergasilus sp, Nothobomolochus sp, Lernea sp and Lepiophtherius sp. The infestation dynamics of parasitic copepods in terms of prevalence, mean intensity and mean abundance were calculated to determine the degree of infestation on each species. A higher prevalence (40%), mean intensity (13.2) and mean abundance (5.3) were found in Liza parsia while Etroplus suratensis had the lesser prevalence. There is a significant difference in the prevalence (p < 0.05), mean intensity (p < 0.05) and mean abundance (p < 0.01) in the rate of infestation of Liza parsia among the stations during the year 2015–2016, where as Oreochromis mossambicus and Etroplus suratensis shows no significant difference in the rate of infestation. The rate of infestation with parasitic copepod was higher in 2015–2016 than in 2016–2017. A higher proportion of fishes were more infested in Choolatheruvu (Station 3) as compared to Ayiramthengu (Station 1) and Valiyazheekal (Station 2).