This policy brief aims to promote better management of aquaculture-based fisheries enhancements (stocking of hatchery fish to improve fisheries) through integrated analysis of enhancement systems and quantitative assessment of management practices through use of the EnhanceFish decision tool.

‘Spawn’ is the name for the young fish about three days old that are available from hatcheries. Sometimes these young fish are also called hatchlings. The spawn of catla, rohu and mrigal is about 6-8 mm long. At this stage, the ‘yolk sac’ is absorbed, the mouth opened and the fins fully developed. Spawn are reared intensively, first to the ‘fry’ size and then to the ‘fingerling’ size. All the three stages are marketed and collectively called ‘seed’.

The “fast fingerling system” can produce advanced fingerlings about two months earlier than they are normally available from fish farms.  The farmer uses just one pond for continuous growing until fingerling size is reached, and fewer fish are stocked. A farmer with a small, seasonal pond can produce fingerlings in one month. These can then be sold for a high price because everyone wants fingerlings as early as possible.

White tail disease in Macrobrachium rosenbergii is emerging as a serious problem in the region. Two viruses, M. rosenbergii nodavirus (MrNA) and extra small virus (XSV) have been found to be associated. The role of MrNV and XSV is not yet clear. Considering the economic impact and potential for the disease to spread, white tail disease (MrNV and XSV) has been listed under non-OIE listed crustacean diseases relevant to the region and NACA/FAO/OIE Regional QAAD list.

The fingerling rearing pond, like the nursery pond, should be free from weeds and predators. Submerged weeds and predators are killed by mahua oilcake, which then acts as a good fertiliser. If there are no weeds, to kill predators and competitors quickly you can just add 100 kg of urea followed 24 hours later by 200 kg of fresh bleaching powder for a 1-ha area of a 1-m deep pond.