Infestation of Ostracoda Vargula tsujii (Myodocopa: Cypridinidae) in Lethrinus ornatus and Carangoides gymnostethus from Pamban, Southeast Coast India and Its Variation in Prevalence and Abundance with Respect to Seasonality

Ostracoda is a diverse group of aquatic crustacean and often infest the fishes and cause huge economic losses. In the present study, the infestation of Ostracoda Vargula tsuji in major food fishes Lethrinus ornatus and Carangoides gymnostethus was studied. A detailed investigation by using biotechnological and molecular tools, it was identified that Ostracoda present in these fishes was Vargula tsujii and the sample was deposited with GeneBank (NCBI MN889442). An attempt was also made to study the abundance and degree of infestation for different seasonality viz post-monsoon, monsoon, presmonson and summer during 2019. Weekly samples were made from Pamban (9.27°N, 79.22°E), Gulf of Mannar, fish landing center and reported the monthly average values. Total 1405 ± 296.5 of L. ornatus were examined during Jan-Dec 2019, of which 285.5 ±70.2 (20.31%) were found infested with Ostracoda and in the case of Carangoides gymnostethus, out of total 1235.9 ± 205.2 fishes examined, 201.4 ± 47.2 fishes were found with infestation i.e. 16.30% but varying with seasonality. Both L. ornatus and C. gymnostethuse fishes had V. tsujii attacked to their gills at a significant level (p < 0.05), was an incidence of occurrence of infestation of V. tsujii in their buccal cavity of the intestinal track but not to the significant level. The infestation of V. tsujii in fishes from Indian water is reported for the first time and its prevalence and abundance level for seasonality are presented in this study.