The Hilsa shad, Tenualosa ilisha popularly known as ‘Hilsa’, is one of the most commercially important fish species in South Asian countries. The species is widely distributed from the Persian Gulf to Bay of Bengal and ascends into estuaries, rivers and brackish‐water lagoons of the Indo‐Pacific region. Recently, the availability of hilsa has drastically dwindled in aquatic systems across this region, due to anthropogenic pressures, mainly intensive fishing and river obstruction by dams and barrages. Climate change may also be contributing to the declining populations. Hence, there is an urgent need for conservation of the species. In addition, hilsa is of great cultural and economic importance among the peoples of Ganga‐Brahmaputra‐Meghna basin, with very high market demand and increasingly high prices, presently an average of around US$ 12 per kg for consumers both in India and Bangladesh. Many attempts at hilsa breeding and culture have been made across South Asia, particularly in India and Bangladesh, since the 1900s. To date, no breakthrough has been achieved in completing the life cycle in captivity. This review provides an insight into the status of artificial breeding, larval rearing and culture of this species, and identifies research gaps that need to be addressed by future aquaculture development programmes for hilsa in South Asia.

Tenualosa ilisha, the Indian Shad, is one of the most important commercial fish of the Indo-Pacific region and the Hilsa fishery in India is dependent on this species. Presently, the fishery resource of the species lies largely within the Bhagirathi–Hooghly component of the Ganga River system. The annual fish catch of Hilsa from the Bhagirathi–Hooghly River has fluctuated over the years ranging between 12,733 and 20,000 t between 2000–2001 and 2010–2012. The monsoon migration of Hilsa commences in July and gradually picks up in August. From September onwards, the magnitude of migration to the freshwater system showed a declining trend. Stretches between Nischintapur and Diamond Harbour downstream, Hooghly Ghat and Kalna in the freshwater tidal zone, and Lalbagh to Farakka in the Bhagirathi River have been delineated as potential breeding grounds for Hilsa. The intense fishing pressure in the coastal estuarine zone almost year round, especially in breeding season, adversely affects the breeding migration, spawning, and recruitment success vis a vis overall fishery of Hilsa in the system. There is an immediate need to implement effective conservation measures to protect breeders, potential breeding grounds, and juveniles for the cause of sustainable Hilsa fishery.

River Brahmaputra is a trans-boundary major river flowing through the northeastern state of Assam, India and is the lifeline of its natural fisheries. In the present article, we discuss eco-hydrobiology (including sediment quality and energy flow) of River Brahmaputra and its important tributaries in the state of Assam, India based on extensive synoptic studies conducted from April 1996 to March 1998, duly collated with past and present studies. Salient aspects of fisheries of the river system in the state (ichthyofauna, biogeography, conservation status, migratory and exotic fish species, trends in fish yield and species composition, fishing crafts and gear) are discussed in light of past and present studies conducted by the Indian Council of Agricultural Research-Central Indian Fisheries Research Institute and others. Fisheries of floodplain wetlands (beels) located in the Brahmaputra valley in the state and their interaction with the river system are also discussed.

The tidal freshwater areas of estuaries have received little attention in ecological research although they are often heavily stressed by environmental impacts. These critical habitats contribute significantly to the biodiversity of the entire estuarine system. The present study aims to describe the fish diversity, assemblage structure and seasonal dynamics through data collected by intensive sampling of the tidal freshwater stretch of the Hooghly estuary (June 2010 to June 2012), the largest estuary in India formed in the Gangetic delta. The tidal freshwater zone of Hooghly has gained importance due to ecological changes during the post-Farakka period since this zone covers 74% of the total estuarine stretch. During the study, a total of 155 fish species belonging to 49 families and 15 orders were recorded from the tidal freshwater zone of the Hooghly estuary. The exotic ornamental fish Barbonymus altus (Tinfoil Barb) has been recorded from the tidal freshwater zone which is the first record of these species in Indian inland waters. A detailed analysis of the fish diversity revealed that of the total 155 species recorded from the study, 19 species have been listed in category of threatened fishes by National Bureau of Fish Genetic Resources (Lakra et al., 2010). This includes 16 vulnerable (VU) species and 4 endangered (EN) species. This signifies the role of tidal freshwater zone as an essential fish habitat due to its rich fish diversity and as a sheltered area which favours the growth and survival of larval and juvenile fish assemblages.