Infectious spleen and kidney necrosis virus-associated large-scale mortality in farmed giant gourami, Osphronemus goramy, in India.

Megalocytivirus cause diseases that have serious economic impacts on aquaculture, mainly in East and South-East Asia. Five primary genotypes are known: infectious spleen and kidney necrosis virus (ISKNV), red sea bream iridovirus (RSIV), turbot reddish body iridovirus (TRBIV), threespine stickleback iridovirus (TSIV) and scale drop disease virus (SDDV). ISKNV-mediated infectious spleen and kidney necrosis disease (ISKND) is a major viral disease in both freshwater and marine fish species. In this study, we report the isolation of ISKNV from diseased giant gourami, Osphronemus goramy, in India. Transmission electron microscopy of ultrathin sections of kidney and spleen revealed the presence of numerous polygonal naked viral particles having an outer nucleocapsid layer within the cytoplasm of enlarged cells (115-125 nm). Molecular and phylogenetic analyses confirmed the presence of ISKNV and the major capsid protein (MCP) (1,362 bp) gene in the infected fish had a high similarity to the other ISKNV-I isolates. Moreover, ISKNV was propagated in the Astronotus ocellatus fin (AOF) cell line and further confirmed genotypically. A high mortality rate (60%) was observed in gourami fish injected with ISKNV-positive tissue homogenate through challenge studies. Considering the lethal nature of ISKNV, the present study spotlights the implementation of stringent biosecurity practices for the proper control of the disease in the country.

Catfishes of the genus Sperata (Pisces:Bagridae) in India.

DNA barcode data of the South Asian bagrid catfish genus Sperata indicate the presence of at least five species in the Indian subcontinent. Those results, which are supported by morphological data, show a marked increase in species diversity from the recent taxonomic and fishery literature, although each of the five species had been previously named. Two species are restricted to rivers of peninsular India south of the Godavari: Sperata aorides from the Cauvery river basin and S. seenghala from the Krishna river basin. Most literature records of S. seenghala from the Ganges-Brahmaputra-Meghna river basins likely refer to S. lamarrii, a species which appears to also be present in the Indus river basin. Some genetic data reported as S. seenghala from the Ganges-Brahmaputra-Meghna river basins refer to S. aorella. S. aor is widespread in the Ganges-Brahmaputra-Surma river basins in India and Bangladesh, extending southwards to the Godavari river.