EFFECT OF ORGANIC FERTILIZATION, SUPPLEMENTARY FEEDING AND STOCKING RATE ON GROWTH PERFORMANCE OF NILE TILAPIA AND SILVER CARP

Six ponds (20X50m2) were stacked by 1000 of Nile tilapia fingerlings for each pond. The six ponds were assigned into two groups, each group com‌posed of three ponds, the first pond was stocked with the first stocking rate (SRI) of silver carp (100/pond), the second pond was stocked with the second stocking rate (SR2) of silver carp (200/pond), and the third pond of each group was stocked with the third stocking rate (SR3) of silver carp (300 fish/pond). the three ponds of the first group had the first feeding treatment (fertilization with 50 kg poultry litter every week for each pond) and the three ponds of the second was exposed to the second feeding treatment (fish feed containing 30% crude protein). Results obtained can be summarized as follows: - Means of body weights of Nile tilapia from the 4th week of the experiment up to the 141h week of the experiment, fed the supplementary feed (containing 30% crude protein) were significantly higher than those fed natural food en-hanced by poultry litter as organic fertilization. Body weights of silver carp showed the opposite trend. - Body weight of Nile tilapia increased with increasing silver carp stocking rate. Increasing silver carp stocking rate as followed by a decrease in body weight of silver carp. - using supplementary feed increased body length and body depth of Nile tilapia more than the other feeding treatment. The opposite trend was obtained with silver carp. - Condition factors for Nile tilapia and silver carp were parallelled with previous fish growth results. the effect of stocking rate on condition factor of Nile tilapia and silver carp varied within the whole period of the experiment. - the values of SGR of Nile tilapia from the first week up to 1415 week of the ex‌periment and within biweekly intervals, showed that using supplementary feed gave higher values than using poultry litter in most intervals. The opposite re‌sults was obtained with respect to silver carp. - Increasing stocking rate increased SGR of Nile tilapia, while decreased SGR of silver carp. The SGR values for tilapia, due to the interaction between feeding treatment and stocking rate, were recorded with fish during the first four weeks as the rates ranged between 3.76 -4.57, while, in the other intervals, the rates had ranged between 0.96 - 2.86. The best SGR values for silver carp were recorded with fish during the first eight weeks (0.37 -1.83), while, in the following weeks, the rates ranged between 0.38 -1.13. - The total yield for Nile tilapia and silver carp at harvesting, after 14 weeks in-creased with each increase in stocking rate. In general the largest fish production (270 kg) for tilapia and silver carp was recorded from the pond provided by the supplementary feed and of the third stocking rate (5143), and the lowest fish yield was (180 kg) obtained from the pond fertilized with poultry litter of the first stocking rate (SR1).