Mohammad Rafiqur Rahman
Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh, Bangladesh
Mohammad Kamruzzaman Hossain
Department of Fisheries, Bangladesh
Golam Mohammad Moshiur Rahman
Solidaridad Network Asia, Khulna, Bangladesh
Sirajum Monira Shanta
Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh, Bangladesh
Naznin Sultana
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh, Bangladesh
Al-Minan Noor
Department of Fisheries, Bangladesh
Rafiul Islam
Department of Fisheries Biology and Genetics, Bangladesh Agricultural University, Mymensingh, Bangladesh
Stinging catfish, Primary nursing, Stocking densities, Growth, Survival, Production
Six earthen nursery ponds of farmer near to Bangladesh Agricultural University Campus, Mymensingh, Bangladesh.
Animal Health and Management
The experiment was carried out for 4 weeks from 1 June to 28 June, 2017 in six earthen nursery ponds of farmer near to Bangladesh Agricultural University Campus, Mymensingh, Bangladesh. The ponds were rectangular in shape and the surface area of each pond was 5.0 decimal (0.02 ha) with an average depth of 0.8 meter. Water of the experimental ponds was drained out and all fish species and aquatic vegetations were removed. After drying, pond bottoms were treated with quicklime (CaO) at the rate of 250 kg ha-1 to kill harmful animals and pathogens. All the ponds were then filled with ground water at a depth of about 0.8 meter. Five days subsequent to liming, the ponds were fertilized with organic manure (cattle dung) at the rate of 2,500 kg ha-1 . Seven days after manuring, the pond water was sprayed with dipterex (1.0 ppm) to eradicate harmful insects and predatory zooplankton. One day after the application of dipterex, 4-day-old fry having an average length of 1.34±0.03 cm and weight of 0.0008±0.0002 g were stocked in the experimental ponds. Three treatments differing in stocking densities of fry viz., 2 million ha-1 (T1), 3 million ha-1 (T2) and 4 million ha-1 (T3) were tested with two replicates each. In order to acclimatize them to the new environment, the fry were not fed for the first day. From the second day of stocking, fry were fed three times (8:30am BDT, 1:00pm BDT and 5:00pm BDT) daily with MEGA pre nursery feed which containing 40% crude protein for the first one week. The rest of three weeks have been used MEGA nursery feed which containing 38% protein. The rate of feeding was 15% of the estimated body weight of fry for the first week, 14% for the second week, 13% for the third week and 12% for the fourth week. Subsequent to stocking, the ponds were manured with organic fertilizer (1, 00 kg ha-1 ) at weekly interval. Fingerlings were sampled weekly by seining with a fine-meshed net for the assessment of growth, health condition and feed adjustment.
Physico-chemical parameters of pond water were monitored weekly between 09.00 and 10.00 hr. Temperature (0C) and dissolved oxygen (mg/l) were determined directly by a digital water quality analyzer Hanna DO meter (Model-HI 9146, Romania), pH by a digital pH-meter (Milwaukee pH meter, Model-PH55/PH56, USA), and transparency (cm) by a secchi disc and ammonia nitrogen by a UV VIS Spectrophotometer water analysis kit (DR 6000TM, USA). Total alkalinity was estimated following the standard method of Stirling and APHA.
Quantitative and qualitative estimates of plankton in the experimental ponds were also taken weekly. Ten liters of water, collected from different locations and depths of each pond were filtered through fine-meshed plankton net (25 μm) to obtain a 50 ml sample. The samples were preserved immediately with 5% buffered formalin in plastic bottles. Plankton density was estimated by using a sub-sampling technique. A Sedgwick-Rafter (S-R) cell was used under a calibrated compound microscope for plankton counting. Plankton cells in 10 randomly chosen squares were counted for quantitative estimation using the formula proposed by Rahman. Biological parameters such as plankton samples were also collected from all the experimental ponds at seven days intervals by filtering 20 liters of water through No. 55 bolting silk plankton net. The samples were immediately preserved in 5% formalin solution and later analyzed in laboratory for qualitative and quantitative estimation of phytoplankton and zooplankton. Planktons were identified up to generic level following the method of Ward and Whipple, Prescott, Needham and Needham and Hossain et al. After 8 weeks of nursing, the fry was harvested by repeated netting, followed by drying the ponds. The live fingerlings were counted and weighed individually. Survival (%) and production (kg ha-1) of fry were then estimated and compared among the treatments. The mean values for growth, survival, production, water quality parameters and plankton abundance of different treatments were tested using one-way analysis of variance (ANOVA) followed by Duncan’s Multiple Range Tes. The level for statistical significance was set at 0.05%.
International Journal of Fisheries and Aquatic Studies 2017; 5(6): 81-85
Journal