MORTALITY IN CAGE FARMED JUVENILE SILVER POMPANOTrachinotus blochii: A CASE STUDY

System and species diversification is considered as hallmark of sustainability of aquaculture industry. In this respect, ICAR-Central Marine Fisheries Research Institute has been engaged in demonstrating culture of silver pompano in marine cages to fisher-folk in different maritime states. However, at times the farming operations are hampered by disease outbreaks often leading to complete loss of stocks. At the marine cage farm of Karwar Research Centre of CMFRI, Karwar an incidence of disease outbreak was noticed during June, 2018 in cultured pompano. The affected fishes had stopped feeding and were lethargic. Excessive mucus secretion at the skin surface and gills were observed. Hemorrhage was present in caudal area with complete loss of scales on both sides. Gills appeared pale with presence of Amyloodinium ocellatum. The base of pectoral fins and dorsal fins also showed signs of hemorrhage. Internally, liver was pale and inflamed.  Pale colored peritoneal fluid was also observed. The bacteria from moribund silver pompano was isolated and identified as Vibrio harveyi based on biochemical characteristics and 16S rRNA gene sequence analysis. The 16S rRNA gene sequence (1418 bp,GenBank accession no. MK100328) exhibited 100 % identity with V.harveyi strains 8TCBS3 (KU525086.1), X11XC19 (KM881533.1). This study concluded the coinfection of Vibrio harveyi and Amyloodinium ocellatum as the cause of mortality in cage cultured silver pompano, Trachinotus blochii.