Optimization of Dietary Protein Level for Cage Aquaculture of Oreochromis niloticus in River Ecosystem of Northern Bangladesh

Md. Shaheb Ali, Md. Akhter Hossain, Nafia Binte Ryhan

Abstract:

Water quality, production and economics of small scale cage aquaculture were studied for a period of four months at the Mahananda river in Chapainawabganj district, Bangladesh under three different treatments of dietary protein level like T1 (25% dietary protein feed), T2 (30% dietary protein feed) and T3 (35% dietary protein feed) of Oriochromis niloticus each with three replications. Cage size (1mx1mx1m), stocking density (150 fish/m3 cage), initial stocking weight of fingerling (15 g) and feed regime (pellet feed, twice daily application at 10% of body weight at the start and 5% of body weight at the end of feeding trial) were same for all the treatments. Water quality parameters (Water temperature, transparency, dissolved oxygen, CO2, pH, hardness, alkalinity and NH3-N) were monitored fortnightly and the growth parameters were measured monthly. The mean values of water temperature, secchi disc transparency, dissolved oxygen, pH, free CO2, alkalinity, total hardness and ammonia- nitrogen (NH3- N) varied from 26.12±2.12 to 26.20±2.33°C, 32.49±8.04 to 32.78 ±8.13cm, 5.42±0.24 to 5.80± 0.20mg/l, 7.28±0.09 to 7.41±0.08, 5.70±0.20 to 5.97±0.18mg/l, 85.32±1.08 to 89.45±1.07mg/l, 95.35±3.65 to 97.81±3.61mg/l and 0.41±0.06 to 0.59±0.07mg/l, respectively. There were no significant difference into mean values of water quality parameters among the treatments and were found within the suitable range. Treatment T3 (35% dietary protein feed) varied more significantly (P < 0.05) than that of others for the mean values of growth parameters (final weight, weight gain, Specific Growth Rate (SGR), survival rate and yield) and Cost Benefit Ratio (CBR). Findings indicated that cage tilapia with 35% protein feed was the suitable technique for small scale cage farming in river. Further research is also recommended to explore the production and economics of tilapia farming in large scale in river ecosystem.

Keywords:

Cage farming, Dietary protein, Economics, Oriochromis niloticus, Production

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