THE GROWTH OF OREOCHROMIS-ANDERSONII (PISCES, CICHLIDAE) FROM THE OKAVANGO DELTA, BOTSWANA, AND A COMPARISON OF THE SCALE AND OTOLITH METHODS OF AGING

Otoliths and scales were used for age and growth determination of Oreo chromis andersonii from the Okavango Delta, Botswana. Marginal increme nt analysis showed that an annulus was formed in both the scales and o toliths during the dry summer period. Using scales, the growth of O. a ndersonii was described by L(t) = 285.27(1-e(-0.26(t+2.02))) mm SL and using otoliths by the equation L(t) = 267.48(1-e(-0.25(t+2.18))) mm S L. Maximum age estimates of 10 years using scales and 13 years using o toliths were obtained and the growth curves were significantly differe nt (p < 0.01). Age estimation using scales tended to over-emphasise gr owth in O. andersonii resulting in larger predicted lengths-at-age. Fo r this reason, otoliths are considered to be more reliable and suitabl e than scales in determining the age and growth of this species.