Hilsa in the context of "Herring"

Forage fish, also called prey fish or bait fish, are small pelagic fish that feed on planktons (i.e. planktivores) and other small aquatic organisms (e.g. krill). They are in turn preyed upon by various predators including larger fish, seabirds and marine mammals, this making them keystone species in their aquatic ecosystems.

The typical ocean forage fish feed at the lower trophic level of the food chain, often by filter feeding. They include particularly fishes of the order Clupeiformes (herrings, sardines, shad, hilsa, menhaden, anchovies, and sprats), but also other small fish, including halfbeaks, silversides, smelt such as capelin and goldband fusiliers.

The Rupnarayan is a river in the state of West Bengal, India. It begins as the Dhaleswari (Dhalkisor) in the Chhota Nagpur plateau foothills northeast of the town of Purulia. It then follows a tortuous southeasterly course past the town of Bankura, where it is known as the Dwarakeswar river. Near the town of Ghatal, it is joined by the Shilabati river, where it takes the name Rupnarayan. Finally, it discharges into the Hoogli River.

It is famous for the Hilsa fish that thrives in its waters and is used in Bengali cuisine. It is also notable for the West Bengal Power Development Corporation Limited (WBPDCL) thermal power plant built along its bank at Kolaghat in West Bengal. The river also passes through Bagnan in Howrah district and forms the eastern boundary of district Purba Medinipur with district Howrah.