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Abstract: Growth performance and survival rate of improved strains (F5 and F6) and unimproved strain of Oreochromis shiranus were assessed. Three stocking densities (5, 7 and 9fish/m3) were used to randomly allocate fingerlings, of mean weight 6±0.6g, into 27 hapas of 9m3 each, fixed in a pond of 700m2 at Bunda Fish Farm, Malawi. Stocking density significantly (P <0.05) affected the growth of the 3 strains though there was no significant difference between stocking density of 5 and 7fish/m3. The highest final weight was noted at a stocking density of 5fish/m3 with an average weight of F6 being 28.1g, followed by the F5 (24.9g) and the unimproved (24.0g) strain. The improved strains had a higher final mean weight (F6: 23.41g, F5: 21.84g) than the unimproved strain (18.70g) but there was no significant difference between improved strains (P >0.05). The apparent genetic gain due to selection between the unimproved strain and F5, F6 strains was estimated to be 16.8 and 25.2%, respectively. Based on this, farmers can be encouraged to use F6 strain at a stocking density of 5fish/m3. The revelation that there was no difference between the improved strains has implications on the continuity of the selection program. [Copyright &y& Elsevier]