Parasitic Infection of an Ornamental fish, Shubunkin Carassius auratus L. imported to Pakistan

The present study was aimed to investigate parasitic infection of an imported ornamental fish shubunkin, a variety of goldfish, Carassius auratus. The body weight and total length of fish ranged from 1.2-11.8 g and 3.311.6 cm respectively. Thirty fishes were examined, 19 fishes were found infected with one or more species of parasites. The prevalence was 63.33%. Five species of parasites belonging to three groups were observed from the fish and identified. These parasites were; monogenean, Dactylogyrus extensus. Gyrodactylus sp., protoazon-, Trichodina sp. Ichthyophthirius multifiliis, crustacean parasite, Argulus foliaceus. The fishes were heavily infected with D. extensus (prevalence 63.3%, mean intensity 22.31). There was significant difference in the infection of left and right gill by D. extensus (χ2=4.28; p = 0.05). The secondary lamellae were severely damaged due to high infection by D. extensus. Gyrodactylus sp. prevalence was 46.6% and mean intensity 27.07. There was significant difference in the infection of skin and fins by Gyrodactylus (χ2=5.29; p = 0.05). The tips of caudal fins were eroded. The infection of Trichodina sp., on gills as well as fins while Ichthyophthirius multifiliis on gills was 16.6% and 20% respectively. Argulus foliaceus had very low prevalence (6.66%) and mean intensity 1.0. Dactylogyrus extensus is found to be the most pathogenic parasite affecting shubunkin compared to other parasite species. These parasites may have escaped detection while sending fish consignment to Pakistan. May be the presence of developmental stages of the parasites has been ignored by the consignment dispatchers. The present situation points our attention to one point that the import of ornamental fishes must be done under strict regulations. The imported fishes must be checked at landing sites to stop introduction of pathogenic parasites into Pakistan.