Rearing Fry to Fingerling

The fries are grown to fingerling stage through a period of 2-3months. For pond preparation, steps followed for clearance of weed and unwanted fishes as well as liming are same as that of the nursery pond management. Other steps specific to this process are as follows-

Manuring and fertilization:

Both organic manure and inorganic fertilizers are applied in rearing pond to increase the natural productivity of the pond which serves as the primary food for the fry.

• i. Organic manure: Cow dung @3000-4000 kg ha-1 is applied as basal dose during preparation after which application of fortnightly installments @500 kg ha-1 is done by mixing with water and spraying over the pond surface. First installment must be applied about 10 days before stocking of fry and after at least 7-8 days of liming. If mahua oil cake is used for removal of unwanted fish, then the basal dose is avoided.
• ii. Inorganic fertilizer: Urea @10 kg ha-1 and single super phosphate @15 kg ha-1 may be applied as fortnightly doses after each installment of application of organic manure (cow dung).

Stocking of fry:

After 8-10 days of application of organic and inorganic fertilizer, the fry of about 25-30 mm in size are stocked in rearing ponds preferably in cool morning hours at the rate of 2-3 lakh ha-1 in various combinations (Table) if individual stocking is not possible.

Supplementary feeding:

•  Rice bran and mustard oil cake are mixed at the ratio of 1:1 by weight for preparing supplementary feed for fry. 'Sushama' the AAU fish feed may also be supplied to the fry for better result. The amount of application of supplementary feed varies depending upon the bodyweight and their age.
•  During first month of rearing, supplementary feed is provided at the rate of 8-10% of the total body weight of stocked biomass, while during second and third month, feed is supplied at the rate of 6-8% and 4-6% respectively of their body weight.
•  Both bag or tray feeding and broadcasting method are found suitable for feeding the fry.
•  For herbivorous fishes like grass carp, aquatic vegetations like Wolfia, Lemna, Spirodela, Azolla, Hydrilla, Valisneria, Naja, Potamogeton etc and grasses like para as well as selected terrestrial and semi-aquatic vegetation should be provided after proper washing and mincing.

Harvesting of fingerling:

Harvesting of fingerlings should be done during morning hours with repeated netting with dragnet of suitable mesh size. Supplementary feeding should be stopped one day prior to the day of harvesting. The rearing ponds can be utilized to raise 2-3 batches of fingerlings in a season with average culture period of 2-3 months per batch.

Economics (For 3 lakh fry ha-1 area/ operation)

A. Capital Cost

B. Recurring cost

For seed production (fry-fingerling)

Production = 1,95,000 fingerlings assuming survival rate 65%

Revenue earned by selling of fingerling @ Rs. 4.00/Piece = Rs. 7,80,000.00

Total operational cost = Rs. 3,34,250.00

Profit: Rs. 7,80,000.00 – Rs. 3,34,250.00 = Rs. 4,45,750.00

% profit over operational cost = 133.36%