Nutrient-laden canal water from Kolkata is the lifeline of two communities: Firstly the fish farmers beyond the eastern fringes of Kolkata who depend upon domestic sewage of the dry weather flow channel as a source of nutrients to sustain plankton production in fish ponds/wetlands; and secondly, the semi-poor city people, who harvest the tubifex worms (Tubifex tubifex) as a livelihood, from a stretch of derelict waterway named Adi Ganga. This article describes the practices of tubifex collectors and the market chain for the worms, which are used as a live feed in the ornamental fish industry and in commercial hatcheries.