Reproductive Performance and Early Growth of Three Strains of Nile Tilapia (Oreochromis niloticus) in Egypt: Abbassa, Kafr El Sheikh, and Manzala

The study compared some reproductive parameters and early growth performance in three Nile tilapia strains
one of which have been improved concerning harvest weight and survival rate (Abbassa) and two non-improved local
strains (Kafr El Sheikh and Manzala).A total of 100 females and 30 males from each strain were stocked into five
separate hapas (3 X 8 X 1m). After 4 weeks conditioning phase five spawning cycles were conducted. Every spawning
cycle 36 females and 12 males from each strain were selected and stocked into six spawning hapas (1 X 2 X 1m), each
group contained two males and six females in order to determine some reproductive parameters. From the production of
first spawning cycle 1000 fry were randomly selected from each strain and transferred to 12 hapas (3×4×1 m), four
replicates of each strain at a stocking rate of 250 fry/hapa for a further growth period of 60 days. The local commercial
strain Kafr El Sheikh showed superior ovary weight (g), gonado-somatic index (GSI), absolute fecundity, and relative
fecundity (31, 41, 40, and 41% respectively) over the Abbassa strain. Manzala strain was also greater than Abbassa
strain in gonado-somatic index (GSI), absolute fecundity, and relative fecundity (20, 22, and 25 % respectively). Fry
number/female and fry number/g. female in Abbassa strain were lower than Kafr El Sheikh strain with 24.1 and 26.4%
respectively and were also lower than Manzala strain with16.3 and 16.01% respectively. All studied reproductive
parameters were significantly higher at June followed with May within 5 months experimental period. As for early
growth performance final body weight and survival rate % of Abbassa strain were significantly (P<0.01) higher than
those of Kafr El Sheikh and Manzala strains. Average daily gain (ADG) and condition factor were also significantly
(P<0.001) higher in Abbassa strain than Kafr El Sheikh and Manzala commercial strains. In conclusion, Abbassa strain
showed the lowest results in all reproductive parameters and the best in the early growth performance.