Production of Fingerlings

The present production of fingerlings in the country has been assessed to be 989.84 lakhs of which 50.20% come from rearing of spawn and fry 48.75% from riverine collection and 1.05% from Bundh breeding. (Fish seed committee report, 1966). The total requirement of the country has been estimated to 14189 lakhs to stock the existing cultivable waters. For that we will require a total of about 28,377.01 acres of rearing area in the country.

It is essential to rear the young fish to fingerling stage before planting them in the stocking ponds in order to provide optimum requirements for growth, propagation and for full protection from enemies. This is more evident in extensive waters such as reservoirs and lakes. Further, the food and feeding habits of young fishes are often different from those of adults and special techniques may, therefore, have to be adopted. This is not often possible in common stocking ponds, where in associations of different size groups and species are raised. The detailed techniques in rearing young fish to fingerling stage have been evolved in various countries to suit the local conditions.

Source Of Fingerlings

Other than rearing of spawn and fry to fingerling stage, the important source of fingerling collection in the country is given below:

State	Name of river/Bundh	Collection centres
Andhra Pradesh	Godavari, Krishna, Manjira, Musi	Polavaram, Katheuru, Sardhana, Nanthane,Maharajpet
Assam	Brahamputra	Panpur, Sataiya, Dhubri Goalpara
Delhi	Yamuna	Ali, Chilla, Nangli, Okhla, Palta, Razapur, Wazirabad.
Gujrat	Narbada	Malsar, Motikoral
Madhya Pradesh	Asan Narbada Subarnarekha	Jareena Kharraghat Susera
Madhya Pradesh	Bundhs Dry Bundhs Wet	Nowgong, Sabersingha Nowgong, Jammonia, Bori
Tamil Nadu	Bhavani Cauvery and its tributaries	Bhavani sagar Bhavani, Mettur

 

Rearing Pond Management

The rearing ponds are larger than nurseries, but smaller than stocking or growing ponds. The optimum depth of water varies with the average temperature of the water and the type of fish cultured. It is seldom more than 1.5 metres in rearing ponds. The usual size of the rearing ponds are 10-20 ares (Are=1000 sq.metres). The management method and practices are practically the same for the rearing ponds as in nurseries with a slight laxity permissible. Time of rearing of fries normally 2 to 3 months and some time up to 6 months.

Eight days prior to stocking of fries, organic manuring was done initially. After a month of initial manuring is done with inorganic manures namely Ammonium sulphate, Single superphosphate and Calcium ammonium nitrate at the ratio of 11:5:1 and at the rate of 1000-1500 kgs per ha per year. For three months of rearing 500-750 kgs per ha inorganic secondary manuring with smaller dosages in number of instalments may yield better results than manuring at a time.

In other countries only inorganic fertilization is done But due to cheaper availability of organic manure in our country, both inorganic and organic fertilization of rearing pond is taken up.

The rate of stocking vary widely. The rate of stocking per hectare in an experiment yielded the following results:

Rate of No.of ponds Area of pond Fingerlings Range of Stocking per ha stocked in ha harve sted after survival With fries 3 months of in % rearing
62,500	4	0.08	23,425-53,650	53.48-85.84
93,750	4	0.08	53,362-75,800	56.89-80.85
1,25,000	4	0.08	92,062-95,900	73.65-76.72

The average weight attained by the four species, namely, Catla, Rohu, Mrigal and Common carp under the above stocking rates were 20.23 gms. in Catla, 37.63 gms.in Common carp. The ratio of catla, rohu, mrigal and common carp was 3:4:1:2. The percentage of survival in the above stocking rate were as below:

Rate of stocking	Average percentage of survival
	Catla Rohu Mrigal Common carp
62,500	87.51	87.66	91.66	68.40
93,750	84.18	85.47	85.20	63.13
1,25,000	71.35	83.65	77.82	66.98

Supplementary Feeding

Stock of fry growing to fingerling size are fed during the first month of rearing with equivalent to the initial weight of the fry and during second and third months—double the equivalent weight of the fry stocked with oil cake and grain bran (1:1 ratio by weight) daily.

Rearing Of Grass Carp and Silver Carp

Advanced fry of silver carp and grass carp were stocked in two 0.08 ha ponds in the ratio of 1:1 and at the rate of 62,500 per hectare in one and in the ratio 8:7 @ 93750 per hectare in the other. The period of rearing was 3 months in the former and 78 days in the later pond. The ponds stocked at lower density was manured wit h cow dung @ 2850 kgs./ha.and inorganic fertilizers (ammonium sulphate, single super phosphate, calcium ammon, nitrate in the ratio of 11:1:1) @ 700 kgs./ha. In two equal installments prior to stocking and two weeks after stocking. They were fed with oil cake and grain bran @ 9 kgs./ha./day and duck weeds (Lemna) @ 400 kgs./ha.occasssionally. The feeding schedule in the pond with higher stocking density was altered to 12.5 kgs/ha/day of grain bran and oil cake mixture and 600 kgs/ha of duck weeds. The final survival figures of advanced fingerlings in low stocking density was 98% for silver carp and 90.8% for grass carp. The production of fingerlings in higher stocking density was 95% for silver carp and 66.3% for grass carp respectively. From the information available in hand it is seen that during three months of rearing, fingerlings of size between 100 to 150 mm could be produced at the stocking density of 1,25,000 per hectare. When the population of a species is low in the pond due to natural mortality or low stocking rate compared to other species, it will grow faster. However, in grass carp, this is not entirely applicable as their growth depend on the available weeds in the pond as the grass carp turns to phyto-phagus, when they are 25-30 mm.size. When fingerlings are reared for longer duration, such pond, which are generally perennial in nature are lost for post fingerling rearing for a few months. During prolonged rearing of six months or more, the percentage of survival is likely to be less than that of three months. So the rearing period to advanced fingerlings to be most suitable to be short duration of three months.