Hilsa Shad

The Hilsa Shad (Tenualosa ilisha) is a large anadromous member of the herring family, widely distributed across the northern Indian Ocean from the Persian Gulf to Myanmar, with its principal populations in the Bay of Bengal. It is the national fish of Bangladesh and holds deep cultural significance across the Indian subcontinent. Adults live in coastal and estuarine marine waters and migrate substantial distances upriver through systems such as the Ganges, Padma, and Irrawaddy to spawn. Some populations remain resident in freshwater year-round. Overfishing during spawning runs and river damming have driven regional management measures, including seasonal fishing bans, aimed at sustaining migratory stocks.

Hilsa Shad have a classic herring-family profile: deep, laterally compressed, and covered in large, highly reflective silver scales.

• Strongly forked tail and a small, pointed head with a protruding lower jaw
• Golden-green iridescent sheen along the back, fading to bright silver on the flanks and belly
• A row of sharp scutes forming a saw-edged keel along the belly
• Typical length 35-60 cm, occasionally larger
• Distinguished from other regional shads by its more compressed body depth and lack of prominent flank spots

Hilsa Shad occur across the northern Indian Ocean, including the Arabian Sea, Persian Gulf, and especially the Bay of Bengal, ranging along the coasts of India, Bangladesh, Myanmar, and Pakistan. The species is anadromous, spending much of its life in coastal and estuarine marine waters before migrating upstream into major river systems, particularly the Ganges-Padma-Meghna and Irrawaddy deltas, to spawn in fresh water during the monsoon season. Some populations become landlocked and complete their entire life cycle within freshwater river stretches. Juveniles use river and estuarine nurseries before migrating downstream to coastal waters as they mature.

Hilsa Shad travel in large schools and filter-feed on phytoplankton and zooplankton using fine gill rakers. Spawning migrations typically peak during the monsoon months, when mature adults move hundreds of kilometers upriver against strong currents to reach freshwater spawning grounds. Eggs and larvae drift downstream, and juveniles rear in nutrient-rich estuarine nurseries before returning to sea as adults. The species' long migratory runs make it highly vulnerable to river barrages and overharvest during spawning season, prompting seasonal closures in several countries. As both consumer of plankton and prey for larger predators, Hilsa Shad play a key ecological role linking river and marine food webs.