SPAWNING AND LARVAE PRODUCTION IN NILE TILAPIA (OREOHORMIS NILOTICUSj BREEDERS UNDER DIFFERENT FEEDING REGIMES.

SPAWNING AND LARVAE PRODUCTION IN NILE TILAPIA
(OREOHORMIS NILOTICUSj BREEDERS UNDER DIFFERENT
FEEDING REGIMES.
BY
M. A. ESSA*
*National Institute of Oceanography and Fisheries, Alexandria, Egypt.
Key words: Fish Reproduction, Nile Tilapia.
ABSTRACT
Reproductive performance and production of Nile tilapia,
Oreohormis niloticus, larvae were tested under two different feeding
regimes. The results indicated that, there is a considerable difference in
food requirements before and after ovulation. Excellent egg and larvae
production can be obtained using thefollowing regime: Shortly after
ovulation afat (9.13 %) and carbohydrate (49.52 %) rich diet should be
used to accelerate the egg development. After the completed
vitellogenesis the females need more protein rich food (25.73 %), less fat
(4.56 %) and carbohydrate (46.93 %)for not only building-up ofsexual
products but also to prevent unnatural fatness of the ovaries. While
when the femalesfedwith diet rich infat (9.13 %), carbohydrate (49.52
%) and protein (25.20 %) all the time, this diet causesfattening ofthe
organs, especially ovaries, and thus reduce normal process of
reproduction.
Egg dimensions, percentage hatch and newly hatched larvae length
were not different ( P< 0.05) among the two feeding regimes.