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Development of Backyard Macrobrachium Hatchery System and Larval Rearing Technique in Different Stocking Density

M. W. A. Pramanik
Fisheries Research Institute, Riverine Station, Chandpur, Bangladesh

G. C. Haldar
Fisheries Research Institute, Riverine Station, Chandpur, Bangladesh

Abstract/ Executive Summary:

Fabrication of backyard hatchery and the technique of prawn seed production developed by the Riverine Station, Chandpur of the Fisheries Research Institute Bangladesh have been described. This hatchery consists of three main components : 1) bio-filter, ii) rearing tank unit (chari) and iii) air blower/air pump unit. Plastic drum of 200-250 I capacity and cement cisterns of 200-2501 capacity were used as bio-filler and larval culture tanks respectively. A 2.2 kw air blower and 5 HP air compressor were used to operate the aeration system in the hatchery. Diluted sea water (10-12 ppt) made from brine solution (200-250 ppt), collected from salt bed) was used in the hatchery system for hatching of eggs and rearing of larvae. Rearing of first stage zoea larvae was conducted in three rearing tanks viz. I. II and III at stocking densities of 40, 50 and 60 per litre of water respectively. 25±0.82 post larvae/litre, 27±1.41 post larvae/litre and 28±1.63 post larvae/litre were produced in tanks I, II and III in 37.41 and 39 days rearing tenure, respectively.

Keywords: Development, Production, Macrobrachium, Hatchery system, Stocking density

Location: Fisheries Research Institute, Riverine Station, Chandpur

Start Date: 00-00-1994

End Date: 00-07-1994

Program Area: Resource Development and Management

Commodity: Prawn

Objectives:

To generate information for setting-up low cost backyard hatcheries even in the remote areas of Bangladesh.

Methodology:

An empty plastic drum of 200-250 litre capacity was converted in to a bio-filter for the Backyard prawn hatchery. The top lid of the drum was cut and removed and 3-4 holes of 1.9 cm dia around the centre were made besides many holes of 1.27 cm dia maintaining 2.54 cm distance on the rest part of the lid. This sieve like lid was used as filter plate for the bio-filter which could be removed by pressing the inner side of the drum, easily. The filter plate was placed 20.3 to 22.9 cm above the bottom with the help of 3 pieces of 10.16 cm dia PVC pipe of 20.3 to 22.9 cm in length. The gap between the filter plate and bottom of the drum was designated as false bottom of the bio-filter. 3 to 4 short PVC pipes of 1.9 cm dia were fitted in the 1.9 cm hole of the filter plate, so that the lower end was prolonged by 2.5 cm, upto lower end of the filter plate. 3 to 4 PVC 'T' of 7.6 to 10.2 cm dia were connected at the upper end of the PVC pipe which was fitted with the filter plate above the bio-filter. Another short piece of 3/4" PVC pipe was also fitted at the outlet of PVC 'T' so that the end of this outer pipe fall at the middle of rearing chari (tank). A polythene tube of 1 cm dia was introduced in to the false bottom through the pipe attached to the filter plate by connecting with line system of air blower and air compressor. The drum was filled up with disinfected gravels of 1 cubic inch dia at a height of 45.7 cm. The treated saline water of 12 ppt was poured in to the drum. A layer of clum shell was spread over the upper surface of the gravel in the bio-filter, for buffer action. In the hatchery a container of 250 litre capacity was made of cement and used as rearing unit. The rearing tank (Chari) was set-up in such a way an a wooden table that the height of the chari was slightly more than the bio-filter. A hole of 1.9 cm dia was made just two inches below the upper edge of the rearing tank and a short PVC pipe of desirable length of same dia was inserted through this hole at 45° angle, so that the other end of the pipe could touch the bio-fillter. The rearing tank was filled with treated saline water of 12 ppt upto the mouth of the PVC out-let. An air blower of 2.2 Kw and 5 HP air compressor were used to operate this mini backyard hatchery along with large scale operation. ln absence of electricity, diesel operated air compressor was used. Fixed quantity of saline water could be reused through filtration and recirculation into closed system backyard prawn hatchery. In the closed system hatchery, unionic ammonia was produced in the recirculatory water through bio-filter and rearing tank due to the metabolic activity of larvae, deterioration of unused feed, Artemia naupli and moulted shell etc. Unionic ammonia caused the mortality of larvae. Before each application the level of inorganic ammonia salt, in the bio-filter was maintained as 0.8-0.9 ppm. Pipes, cover, gravels and other inputs needed for hatchery operation were disinfected by soaking into a solution of 12 ppm bleaching powder containing 60% chlorine for 12 hours. After 12 hours, all the materials were washed with fresh water to remove the smell of bleaching powder. Brine solution (240 ppt) was diluted to 12 ppt with fresh water in a cemented mixing tank and then treated with 1ppm bleaching powder for the destruction of harmful bacteria. This brackish water was kept stable in the tank for three days and again treated with 12 ppm sodiumthiosulphate and aerated vigorously for a day and allowed to remain stable for 24 to settle the suspended particles. The sedimentized and supernatant water was transferred to filter bed and rearing tank (chari) after filtering with cotton bags. Larvae were reared in nine rearing tanks (chari), each containing 40 litres of brackish water at the Fisheries Research Institute, Riverine Station, Chandpur in July 1994. The charies were connected to three hie-filter. The larvae were reared in chari maintaining the water parameters; temperature at 28 to 30°C, oxygen at 4.7 to 7 mg/I; pH at 7.5-8.5 and salinity at 12 ppt. The larvae were fed with artemia naupli twice a day at 07:00 and 16:00 hrs for the first 10 days maintaining the density of 5 BSN/ml. After 10 days, the larvae were fed with prepared feed containing 30% egg yolk, 25% milk powder, 35% clum/fish muscle, 6% arrorot, 3.5% yeast powder, 0.2% oxytctracycline and 10 drops multi-vitamin at the rate of 500% body weight, 4 to 5 times a day besides artemia naupli 2.5/ml at night. The unused feed, moulted shell and other waste materials were siphoned out prior to every feeding time

Source of Information: J. Inland Fish. Soc. India, 28 (1), 1996 : 21 - 27

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

In the present study per litre larvae production in all treatments were satisfactory. Larvae production (27 PL/I) in treatment II was the highest among all the treatments and was also higher than the earlier production of 11.93 P/I, 10.22 PL/I and 18.9 PL/I in static green water as well as 9.5 PL/I in closed recirculatory system. The larvae preferred larger food particles rather then smaller ones. They showed cannibalistic tendency if sufficient food was not provided. The results and technique adopted in the present study indicated low operational cost of the backyard prawn hatchery. Potential prawn farmers of Bangladesh can adopt this hatchery system to mitigate the demand of prawn seed.

Knowledge Management: Journal