Abstract:
The abundance and composition of parasitic fauna change with fish size (age) and sex. The present study investigates the occurrences of parasites with sex of the fishes collected from Valaichenai lagoon. Samples were taken at different localities in Valachenai lagoon over the dry and wet season for the period often month5 from June 2009 to March 2010. The host fishes: Ambassis gynocephalus, Arius bilineatus, Caranx sexfasciatus, Epinephelus coioides, Entroplus maculates, Etroplus suratensis, Gerres abbreviated, Hemiramphus far, Leiognathus fasciatus, Lutjanus russeli, Mugil cephalus, Siganus javus, Siganus lineatus, Sphyraena jello, Tachysurus sp, and Tilapia niloticus were collected either from cast net sampling or local fishermen were examined for parasites. The overall prevalence of parasites in the host fish was 70.28% in female and 29.71% in male fishes. The results obtained revealed that sex did not much influence the degree of parasites infection in fishes except Ambassis gynocephalus, Etroplus suratensis and Tachysurus sp. The copepod Ergasilus parvitergum showed the highest prevalence and intensely and was the most common parasites on the examined fish. The migratory behavior of adult to offshore waters, and their eventual return to the lagoon, accounts for much of the variability observed in the distribution of some parasitic species
