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A laboratory experiment was carried out to investigate the effect of Thepax and Endo Vit. C as feed additives in the formulated diet on the growth performance of grass carp Ctenopharyngodon idella. The feed (30.11% crude protein) manufactured in the laboratory using raw local materials diet. Young grass carp (Average weight 3.36± 0.95 g) obtained from Aquaculture Unit ponds in Al-Hartha Station for Agricultural Researches, North Basrah. The fish were stocked in nine glass aquarium, three replicates for each treatment, of dimensions 60×40×30 cm provided with pumping aeration. The experimental diets included a control T1 (0% additives), T2 (1g Thepax/kg diet) and T3 (1g Endo Vit. C /kg diet) were used in feeding trail of current experiment. The experiment lasted for 57 days (from 29 Nov. to 24 Jan.) and fishes were fed six days a week using 5% of fish weight as feeding ratio. Results of current study reveals that grass carp fed on formulated feed supplemented with Endo vit. C having high growth performance (WG, DGR, RGR and SGR). The lowest Feed conversion ratio (2.511) was recorded in T3 this value was statistically significant (P≤0.05) with T2 while the highest value (2.767) was observed on the control. Protein efficiency ratio, feed intake and gross conversion efficiency were also recorded high values in T3, but control displayed superior values compared with Thepax treatment, which showed higher value of Relative feed intake compared to other two treatments.

A comparison was conducted for growth criteria of common carp, Cyprinus carpio larvae cultivated in earthen ponds and recirculation aquaculture system (RAS) depending on live foods (phytoplankton and zooplankton stimulated by buffalo fertilizers in earthen ponds, while the larvae cultivated in RAS were feed on Artemia larvae reproduced in vitro, in addition to manufactured pellets (38% crude protein) for common carp in both systems. Three 2500 m2 earthen ponds were cultivated for 90 days with larvae of initial weight 0.002 g at different numbers (40800 larvae for pond 1, 55600 larvae for pond 2 and 36400 larvae for pond 3). These larvae depend on natural food for 19 days, then fed on manufactured feed. Fishes were weighed every 19 days to change daily feed. Three replicates of RAS plastic tanks (100 letter capacity) cultivated for 90 days with 0.002 g larvae at a density of 2 larvae per one liter (160 larvae at each plastic tank). These larvae fed for 15 days to saturation (4 meals daily) with Artemia larvae and small Artemia, then fed on manufactured feed. Subsequently, fishes were weighed every 15 days to change daily feed. Larvae cultivated in earthen ponds recorded weight gain of 26.90 g, daily growth of 0.30 gday-1, relative growth of 1345000%, specific growth of 10.56 %day-1, feed conversion of 1.25 and survival rate of 13.16%. Larvae cultivated in RAS system recorded weight gain of 1.53 g, daily growth of 0.02 gday-1, relative growth of 76200%, specific growth of 7.37 %day-1, feed conversion of 2.82 and survival rate of 72.32%. Statistical analysis of results revealed significant differences (p>0.05) in all growth criteria for larvae cultivated in both systems. Final conclusion that earthen pond was better than RAS systems in producing fingerlings of common carp.

The early development of common carp (Cyprinus carpio L., 1758) was studied from fertilizing until juvenile stage. The series developmental staging was done using morphological characteristics. Results identified eight main periods of embryogenesis: zygote, morula, blastula, gastrula, neurella, segmentation, pharyngula and hatching period. Results also identified and described nine larval development stages: hatching larva stage, rudimentary - pectoral fin and gill arch stage, melanoid-eye with gas bladder emergence stage, one chamber gas bladder with yolk absorption stage, two chamber gas bladder stage, pelvic fin bud with dorsal fin formation stage, anal-caudal and pelvic fin formation stage, squamation stage and juvenile stage. Hatching occurred at 38h after egg fertilization. The fertilized egg was spherical, yellowish, transparent and 2.5 mm in diameter. The transition from larva to juvenile occurred in 30 days.