Theses and Dissertations

Title: Comparison of four strains of Oreochromis mossambicus for selected aquacultural traits

Name: Wixson, Jeremy M.

Degree: MS

Chair: Ronald P. Phelps


University: Auburn University

Location: Auburn, Alabama

Date: 2004

Pages: 71

Keywords: aquacultural traits, Oreochromis mossambicus, sex-reversal, fecundity, nursery growth, hatchery


Four strains of O. mossambicus, Zulu Normal, Zulu Red, Seshego, and Venda, were compared for fecundity, sex reversal, nursery growth, and growth of one-year old males. No strain showed a production advantage in any of the traits studied. Fecundity ranged from 586.1 to 2,586.3 fry/Kg female for Zulu Red and Venda respectively. Venda produced the largest number of fry/Kg mostly because of the small size of females compared to the other three strains. Growth and survival of sex-reversed fish was poor among all strains due to high mortalities during the second and third week of sex reversal. Growth rates ranged from 0.01 to 0.04 g/day for Seshego and Venda respectively. Survival ranged from 33.1 to 42.1 % for Zulu Red and Seshego during trial I of sex reversal, and 3.8 to 13.3 % for Seshego and Venda respectively during trials II and III. The cause of poor survival is not known, but is thought to be water quality related, due to high mortalities in one night during the third week of sex reversal. Sex reversal produced 65.1 to 86.2 % males for Seshego and Zulu Red respectively. Survival during the nursery phase ranged from 5.5 to 42.8% for Zulu Normal and Venda respectively. Growth was poor in Venda compared to Seshego and Zulu Normal. Standing crops after the growth of one-year old males over a 30 day period ranged from 5.8 to 9.2 kg/ha day-1 for Seshego and Zulu Normal respectively. FCR ranged from 3.5 to 7.3 for Zulu Normal and Seshego respectively. Survival ranged from 90.0 to 101.7% for Seshego and Zulu Normal respectively.

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