Effect of feeding frequency and stocking density on the performance of mono sex Nile tilapia in concrete tanks [electronic resource].

Includes reference.

A 22-weeks factorial design 2 x 3 x 2 (two feeding frequencies, three stocking densities and two replicates) rearing trial was conducted in concrete tanks with average initial weight of 2.8 ± 1.3 g/fish and average initial length of 5.2 ± 0.9 cm/fish of mono-sex male Nile tilapia, Oreochromis niloticus, to examine the effects of two feeding frequencies (2 and 4 times daily) and three stocking densities on growth performances, production traits, feed utilization and body composition. Twelve concrete tanks 4 m3 each (2 x 2 x 1.25 m, long, width, and height) were stocked with either 200, 400 or 600 fish for each tank to give a stocking rate of 50, 100 and 150 fish /m3 , respectively and maintained at a flow rate of 8 Umin. The results revealed that, mean final weight (g/fish), mean final length (cm/fish), gain in weight (g/fish), gain in weight %, gain in length %, daily gain (g/fish), SGR (% per day) were significantly (P≤ 0.01) the best at the lowest stocking density. While, total production and net production exhibited significantly (P ≤ 0.01) the opposite trend. Harvests and production estimates increased with increasing stocking density. No significant differences (P > 0.05) were found between feeding frequency in terms of gain in weight, mean final length, gain in weight (%), gain in length (%), average daily gain (g/fish), SGR (%/day), feed conversion ratio (FER), feed efficiency ratio (FER), protein efficiency ratio (PER) and total feed intake (g/fish). While mean final weight (g/fish) and all production traits were significantly influenced by feeding frequency. The highest stocking density (150 fish/m³) had significantly the best FCR, FER, PER and feed intake (g/fish). Whole body moisture, ash and crude fiber contents were not significantly affected by either stocking density or feeding frequency. Whole-body protein content was significantly affected by stocking density, but not significantly affected by feeding frequency. While whole body crude fat content was significantly affected by feeding frequency, but not significantly affected by stocking density it can be concluded that, stocking density of 150 fish /m³ of mono-sex male Nile tilapia reared in concrete tanks at feeding frequency of four times/day exhibited the highest production and net profit and would seem to be the most desirable density under this system conditions.

Summary in Arabic.

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