Influence of water quality on fish productivity
2010
M. A. El Bably | H. H. Emeash | Asmaa N. Mohamed | Nahla R.
The physical, chemical and bacteriological parameters of water in fish ponds were investigated with a view to optimize the conditions for fish productivity by using three private fish farms with different water supplies. Water and fish samples were collected equally from each pond over a period of 17 months. Water temp., Dissolved oxygen (DO), pH, Ammonia, Nitrite, Nitrate, and bacterial count were determined. The average values of bacterial, parasitic, survival and growth rates of fish were also assessed. Results revealed that pond water in farm (III) had the highest averages of temperature nitrite, nitrate 31.8±1.5, 8.18± 0.9, 0.41 ± 0.06 , 3.79 ± 0.6 resp., with the least content of DO 3.6 ± 0.7 followed by farm (II),which had also the highest mean values of NH3 - N, total coliform and fecal coliforms were 3.15±0.65, 59.0 & 18.5 followed by ponds of farm (III), while, the lowest averages of estimated parameters were recorded in farm (I).Correspondingly, fish samples of farm (III) showed the highest level of total bacterial, coliform, fecal coliform count and parasitic infestation; were 42.5±5.4, 29.6±3.6 , 11.3±3.1 and 31.15% respectively, followed by fish of farm(II) 29.75±3.5, 11.5±3.3, 7.4±1.1 and 10.8 % respectively, Meanwhile, fish in farm (I) showed the lowest value of both bacterial contents with no parasitic infestation which explain the highest percentages of daily weight gain & survival rates 35.2±4.4 gm. & 97.0 ±1.6 % respectively. Throughout study period compared with those in farms (III & II) respectively, resulting from poor water quality & parasitic infestation which acts as stressors affecting fish health and productivity. Therefore, fish productivity can be enhanced if the water quality in the ponds were maintained at optimum levels.
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