The Effect of Stocking Density and Supplementary Feeding on Growth Performance and Yield of Nile Tilapia [Oreochromis Niloticus (L, 1758)] in Cage Culture in Wonji Reservoir Ethiopia
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Date
2010-06
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Addis Ababa University
Abstract
This research was conducted to investigate the effect of stocking density and supplementary
feeding on growth performance and yield of Oreochromis niloticus in cage culture in Wonji
Reservoir. The treatments had stocking densities of 25 (25F), 50 (50F), 75 (75F) with
supplementary feed and 25 (25N), 50 (50N), 75 (75N) fish per m3cage without supplementary
feed. The treatments with supplementary feed were in duplicates and the controls were single.
Juveniles with average weight of 43.70 ± 0.19, 43.12 ± 0.5, 43.38 ± 1.14, 43.97 ± 0.36, 43.51 ±
0.33 and 43.98 ± 1.18 gm were stocked in 25F, 50F, 75F, 25N, 50N and 75N treatments,
respectively. The fish were fed 3% of their body weight twice per day using feeding trays for
100 days. The results indicated that growth performance of O. niloticus was density dependent.
The final mean weight of O. niloticus in 25F was 175.83±0.68 gm and the mean daily weight
gain was 1.36 gm, whereas in treatments (50F, 75F) and controls (25N, 50N and 75N), final
mean weight was 154.92±0.82, 146.70±0.15, 86.67±0.51, 73.64±0.26, 72.62±0.46 gm and
mean daily weight gains were 1.06, 0.77, 0.55, 0.28 and 0.27 gm, respectively. Moreover, feed
conversion and condition of fish were affected by stocking density and supplementary feeding.
The apparent feed conversion ratio (1.45 – 4.45) was significantly affected by stocking density
(P<0.05). Fulton condition factor was inversely affected by stocking density while it was
directly affected by supplementary feeding. However, survival rate was not affected by stocking
density and supplementary feeding (P > 0.05). In this experiment, it can be concluded that the
most effective stocking densities for O. niloticus cultured were at 25 fish / m3 cage for larger
size fish demand in short period and 75 fish/m3 for higher gross production with
supplementary feed. Physical, chemical and biological parameters were the same among cages
or between cages and the open water in the present experiment. Thus, all O. niloticus had
similar culture environment and equal access to natural feeds.
Key words / phrases: Cage culture, Growth performance, Wonji Reservoir, Nile tilapia, Stocking
density, Supplementary feeding.
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Keywords
phrases, Cage culture, Growth performance, Wonji Reservoir, Nile tilapia, Stocking density, Supplementary feeding.