'n Vergelykende studie van die groeivermoëns van vier tilapia spesies in natuurlike en intensiewe produksie-eenhede

English: The growth rates of four tilapia species were compared under natural and intensive conditions. This was done to find the fish species most suitable for fish farming purposes in South West Africa. All four species showed a high growth rate in their first year until they reached sexual maturity. Significant differences between the empirical lengths of certain age groups were found between O. mossambicus (Hardap dam), O. macrochir and T. r.rendalli from the Okavango and Cunene rivers. Significant differences between the empirical lengths of all the age groups were found between O. andersoniii from the Okavango river and O. macrochir from the Cunene river. Significant differences between empirical lengths of certain age groups were found in O. andersonii from the Okavango river, O. macrochir from the Okavango river and T. r.rendalli from the Okavango and Cunene rivers. O. macrochir and T. r.rendalli from the Okavangoriver showed the best length/mass ratio, followed by O. macrochir from the Cunene river and O. andersonii from the Okavango river, O. mossambicus from Hardap dam and lastly T. r.rendalli from the Cuneneriver. O. macrochir from the Okavangoriver were found to be superior in length and mass to their counterparts in the Cuneneriver. After 84 days of hormone treatment, O. mossambicus and O. andersonii fingerlings showed the best growth rates with feed conversion rates of 2,6 and 2,2 respectively, followed by O. macrochir iwth a feed conversion rate of 2,7 and lastly T. r.rendalli with a feed conversion rate of 3,0. In the control group O. andersonii showed a better growth rate than O. mossambicus with feed conversion rates of 2,4 and 2,6 respectively. There were no significant differences in the growth rates of O. mossambicus and O. macrochir in the control group, with O. macrochir having a food conversion rate of 2,9. T. r.rendalli showed the poorest growth rate in the control group with a food conversion rate of 3,5. No correlation could be found between the mass of the female and the growth rate of her offspring. With the exception of O. andersonii, the hormone treatment O. mossambicus showed a better growth rate after day 84. O. macrochir after day 98 and T. r.rendalli from day 14, than the control group.