Md. Abdus Samad
Dept. of Fisheries, University of Rajshahi, Rajshahi-6205
Sharmin Hasan Mimi
Dept. of Fisheries, University of Rajshahi, Rajshahi-6205
Alok Kumar Paul
Dept. of Fisheries, University of Rajshahi, Rajshahi-6205
Md. Selim Reza
Fisheries, CEGIS,Dhaka-1212, Bangladesh
Oreochromis niloticus, Survivability, Monosex, Water quality
Department of Fisheries, University of Rajshahi
Animal Health and Management
Study location and pond facilities: The experiment was performed in nine earthen ponds of 0.004 ha in the hatchery complex, Department of Fisheries, University of Rajshahi for a period of 14th June to 13th August, 2013. The ponds were similar in shape, depth, basin configuration including water supply facilities. The water depth was maintained around 1.0 m using machine at regular interval.Experimental design: Experiment was conducted under three treatments namely T1, T2, and T3 each with three replications. Stocking density of Oreochromisniloticus the pond under each treatment was 249964 individual/ha (initial weight 0.13±00g). Pond preparation: At first the bottom and sides of the selected ponds were repaired and all the aquatic weeds were removed manually by hand picking, uprooting and cutting from the nursery pond. All ponds were treated with lime at the rate of 247 kg/ha to disinfect the water. Then the experimental pond-1, pond-2 and pond-3 were fertilized by using cow dung-988 kg/ha, urea-24.7 kg/ha, TSP-12.35 kg/ha after 7 days of liming (DOF, 2002). The source of water of experimental ponds was rainfall and deep tube-well. During the introduction of water in each experimental pond, fine mesh (2 mm) nylon net hapa was used in the mouth of the pumped water to prevent predatory fish egg, spawns, fry and adult or larvae of aquatic harmful insects to inhabit their entrance. Then natural food production was tested and the water toxicity of the experimental ponds was checked. Netting was done to remove small frog and water bug from the experimental pond before 3 days of fry stocking. Collection and stocking: Larvae of Monosex tilapia were collected from Natore Govt. Hatchery, Natore. Larvae were kept inside the polythene bag with proper oxygen and the mouth of the polythene was bound tightly by rope. Then the larvae were brought and were transferred to the experimental pond and were acclimatized for about half an hour. Before releasing the larvae to the experimental pond the initial length and weight of 10larvae were recorded with a sensitive portable electric balance (KD300kc: 0.01g-300g). Initial weight of larvae was 0.13±00g respectively. Fry were acclimatized with experimental pond water in plastic bag and released in each experimental pond at 8:00 am at the rate of 1012 individual/dec. in Treatment T1,1012 individual/dec in Treatment T2and 1012 individual/dec in Treatment T3. Feed preparation and feeding: The required quantities of all ingredients mixed with hand (prepared feed) and spread it to the experimental pond surface. The supplemental feed was given to fry at the rate of 10%, 8% in 1st, 2nd Month respectively. Quantities of feed were adjusted every seven 15 days interval on the basis of increase in the average body weight of the stocked biomass. Half of the ration was supplied at 9.00 am and remaining half was supplied at 4.00 pm. Sampling: Sampling was done on every fortnight interval in the morning (09:00 am to 10:00 am). Length and weight were recorded by random sampling of 10 fry from each experimental pond by using a small net. Weight was taken with an electric balance and length was recorded with measuring board. All the collected data were recorded in a note book and finally calculated the average length and weight of fry according to treatment on each sampling day. Water quality monitoring: Physico-chemical parameters like water temperature (0C), transparency (cm), Dissolved oxygen (mg/l), NH3-N (mg/l), pH, Alkalinity (mg/l) of each experimental pond were measured at 15 days interval. Temperature (0C), Transparency (cm), Dissolved oxygen (mg/l), NH3-N (mg/l), pH, Alkalinity (mg/l) of water of each experimental pond under each treatment was recorded on sampling dates. Temperature was recorded by using a Celsiusthermometer, transparency was recorded by secchi disc and other chemical parameters were recorded by using Hack kit box (DR/2010 model, HACH, Loveland, CO, USA, a direct reading spectrophotometer) at the pond site. Recording of water quality data were done between 09:00 am and 10:00 am. Growth parameters: Growth, length in (cm) and weight in (g) was measured in every 15 days interval. To evaluate the fish growth the following parameters were measured: weight gain (g), length gain (cm), percent weight gain, percent length gain, SGR (%), survival rate, yield/kg/ha/2 months.
J. Biosci. Agric. Res. 10(01): 848-856
Journal