The practical work of the present experiments was carried out at the World Fish
Center, Abbassa, Abou Hammad, Sharkia, Egypt. The experiment aimed to
investigate the effect of spawning month (April and May), dietary protein level (25 or
35%) and protection of spawning tanks (covering or uncovering of the spawning
tanks) on fry production and average fry weight of the Nile tilapia. The obtained
results can be summarized as follow:
- Fry production/tank were found to be 6462 and 19082/tank during the two months
April and May, 10719 and 14824/tank for the two dietary protein levels, 25 and
35% and 16428 and 9115 fry/tank for the covered and uncovered tanks,
respectively and the differences in fry production due to the effect of spawning
month, dietary protein content and tank protection were significant.
- Averages of individual fry weight as affected by month, dietary protein levels and
pond protection were found to be 0.025 and 0.016 g during the two months April
and May, 0.021 and 0.019 g for the two dietary protein levels, 25 and 35% and
0.018 and 0.023 g for the covered and uncovered tanks, respectively. Spawning
month and tank protection significantly affected individual fry weight while
dietary protein levels had no significant effect on fry weight.
- The interaction between the studied factors affected individual fry weight of the Nile
tilapia indicated that the highest average individual fry weight was recorded for fish
group raised in covered tanks and received the lower protein content during April.
On the other hand, the lowest average individual fry weight was recorded for
broodfish raised in an uncovered tanks and received the higher protein level (35%)
in May.