Comparative growth and survival of diploid and triploid mozambique tilapia (Oreochromis mossambicus) reared in indoor tanks

In the present study, the effect of cold shock on fertilized eggs of Oreochromis mossambicus was during triploid production. Two males (150 ? 224 g) and six gravid females (150 g to 264 g) were collected. The females were injected with ovulin at a dosage rate of 0.5ml kg(-1), the eggs were stripped into a dry bowl, fertilised with milt, divided into two groups (A and B) and incubated. After three minutes, group A was cold shocked at 50C for a period for 5 min, while group B was incubated normally. Tilapia larvae hatchlings were triplicated and stocked at a density of 200 larvae / liter in the aquaria for four weeks. Results showed that triploid fish had a lower hatchability (58%) and survival rate (47%) than diploid fish (of 85 and 70%, respectively), but a higher specific growth rate of 1.097 as compared to diploid at 0.931. While the improved growth rates have great commercial applications. Further research should be conducted to improve the lower hatchability and survivability of triploid tilapia

Patterns of colour inheritance from crossbreeding between Red hybrid tilapia (Oreochromis sp.) and GIFT tilapia (Oreochromis niloticus)

Aim: Methodology: Results: Interpretation: Key words: To examine the pattern of colour inheritances from crossbreeding between Red hybrid tilapia (Oreochromis sp.) and GIFT tilapia (Oreochromis niloticus). A total number of 60 broodstock of 30 each of GIFT and Red hybrid tilapia were selected to produce the first filial generation (F ) and its 1 reciprocal nF . Pairing of female to male were done in the ratio of 3:1. The same breeding scheme were used to produce the second filial generation (F ) 1 2 and its reciprocal nBcF1. Crossbreeding between Red hybrid tilapia male and GIFT female (F ) produced phenotypic colours ranging from red (64.61%), wild type 1 (11.54%), red with blotches (4.96%) and mixed red-wild type (18.87%). The reciprocal cross between GIFT male and Red hybrid tilapia female (nF1) produced phenotypic colours ranging from red (19.65%), wild type (64.62%), red with dark blotches (4.03%) and mixed red-wild type (11.46%). The second filial (F ) generation 2 produced phenotypes comprising of 61.17% wild type, 14.37% red with dark blotches, 20.04% mix red-wild type and 4.40% red type. The backcross (BcF ) produced 10.57 %, faded wild type 22.76 %, red with 1 dark blotches, 28.41 %, red with dark posterior and 60.46 % red phenotype while the reciprocal (nBcF ) produced 52.89% faded wild 1 type, 15.11% red with dark blotches, 6.83% mix red-wild type and 25.15% red phenotype. Manifestation of intermediate and mixed colour phenotypes in F hybrids and deviation from a simple dominant 2 inheritance might indicate an incomplete dominant inheritance, colour determination in tilapia in this study might be located or linked with the male Y-chromosome due to the fact that more reddish coloured fish were produced when Red hybrid tilapia was selected as the parent