Identification and Comparison of Three Tilapia Nilotica Strains for Selected Aquacultural Traits

 Ali Abd El-Aziz Khater

A Dissertation Sumitted to the Graduate Faculty of Auburn University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

Auburn. Alabama 1985

Introduction

Tilapias are members of the family Cichlidae (perch-like African fishes) and are among the most important cultivable fishs pecies in the world (Bardach et al., 1972). They possess several desirable characteristics which recommend them for culture on wider scale in the tropics (Lowe, 1955; Kelly, 1956; Hickling, 1960, 1963; Swingle, 1960; Lovshin, 1975). 

The most commonly cultured species are Tilapia aurea, T. hornorum, T. mossambica, and T. nilotica. T. hornorum and T. mossambica are less desirable: T. hornorum has dark color and is not very hardy, while T. mossambica is extremely hardy but has a low growth rate. The T. Niltica and its relative T. aurea have been widely introduced due to their reportedly good growth rate (Chimits, 1957; Bardach et al., 1972; shehadeh, 1976). T. nilotica is a preferred species because it feeds on plankton and detritus, but also utilizes agricultural by-products and animal wastes as well as pelleted feed (Nerrie, 1979).

A number of studies have documented yields of T. nilotica in different locations with different aquaculture systems (Smitherman et al., 1978; Burns and Stickney, 1980), but no research has focused on the potentials which may exist variations among the many geographical populations.

The general objective of this research was to compare three T. nilotica populations (strains) of know geographical origin (Egypt, Ghana, and Ivory Coast). Specific objectives were:

1. to identify the three strains using electrophorises, color meristics and morphometrics, and
2. to evaluate the three strains for the following traits: (a) cold tolerance, (b) reproduction, (c) growth, and
3.  to compare growth of nine possible crosse among the three straints.

Table of contents

•  Literature Review
•  Materials and Methods

 Experimental Facilities

  Experimental Animals

 Tilapia nilotica (Egypt

   Tilapia nilotica (Ghana)

 Tilapia nilotica (Ivory Coast)

  Marking Technique

Eperimental Procedure

  Strain Identification

  Electrophoresis

  Color and Morphology

 Cultural Traits

       Cold Tolerance – Reproduction - Growth      Statistical Analyses

•  Results and Discussion

        Strain Identification

   Electrophoresis

   Color and Morphology

    Cultural Traits

Cold Tolerance – Reproduction - Growth Reproduction

Fry to Subadult

Subadult to Marketable size

•  Summary and conclusions

Prep. / Ayman Ashry
Rev. / Asmaa Ahmed
Manage. / Zeinab Osman