VPP 322: Aquatic Animal Diseases, Health Care and Management (1+1)

POST LARVAE / FRY REARING 

• Preparation and maintenance of nursery, rearing and stock ponds are important steps in carp hatchery operation. Larval rearing in a crap hatchery has two distinct phases.
  • Rearing of postlarvae to the fry stage, which is done in nursery ponds
  • Rearing of fry to the fingerling stage which is done in rearing ponds
• Before stocking in the nursery ponds, the ponds should be fertilized with both organic and inorganic manure and leave it for the production of plankton which serve as the food for fry of fishes. Before  stocking postlarvae, it is necessary to make an estimate the types and abundance of plankton present. The stocking rate of postlarvae in a nursery pond depends on the management practices intended. Natural food in the form of zooplankton is to be produced by continued pond manuring. Supplementary feeds are also to be given if facilities exist to remedy oxygen deficiency condition.
• The fry are netted from the nursery ponds and released in rearing ponds which are to be prepared in the same manner as the nursery ponds. For rearing of carp fry to fingerlings, either monoculture (or) polyculture in any species combination may be carried out. The stocking density of fry (measuring 25.4 mm to 37.8 mm weighing 0.15 - 0.75 g) may be 1,25,000 /ha - 2,50,000/ha. The fry may also artificially fed with oilcake of groundnut (or) coconut and ricebran in the ratio of 1:1. In the case of nursery ponds, harvesting may be done by repeated netting with fine meshed nets in rearing ponds. When fry are grown to fingerling stage, periodical harvesting may be done at an appropriate time to avoid overcrowding.