Pond farming of Nile tilapia, Oreochromis niloticus (L.)j in northern Cameroon. Controlling a sexing error of 1% in hand-sexed male tilapia monosex culture by African catfish, Clarias gariepinus (Burchell) |
| |
| Authors: | A J Middendorp |
| |
| Institution: | Department of Fish Culture and Fisheries. Wageningen Agricultural University, Wageningen, The Netherlands |
| |
| Abstract: | Catfish (mean W0 189 g) were added to ponds (525 mJ each) stocked with 230 hand-sexed, male tilapia (Wu163 g), at 0.04, 0.10 and 0.15 catfish m?2. In each pond, two female tilapias were introduced, thereby creating a sexing error of less than 1%. Feeding was fixed throughout the experiment at 2.5 kg of cottonseed cake per day per pond 6 days per week (mean feeding rate R = 41 kg ha?1 day-1). Rearing time was 125 days. Average net pond production per treatment (ranging between 7.5 and 7.9 t ha?1 year?1) and marketable production were not different between treatments but net tilapia production was significantly lower at the highest catfish density. Both catfish and tilapia growth were negatively correlated with catfish density due to feed competition near the end of the experiment. It was concluded that catfish efficiency in controlling tilapia recruitment was strongly reduced by the availability of supplementary high-protein feed. Large catfish competed with the parent tilapia for the cottonseed cake but apparently did not exploit the tilapia recruits. Yield of tilapia recruits was lowest at the highest catfish fingerling density, although this was not significant. The number of catfish fingerlings was significantly higher at the lowest catfish density, which indicated that large catfish preyed on catfish fingerlings. |
| |
| Keywords: | |
|
|
