Aspects of Growth and Reproductive Biology among three Tilapiines on Lake Kariba

Abstract

The growth and reproductive biology for three Tilapiine species, Oreochromis andersonii, Oreochromis niloticus and Coptodon rendalli on Lake Kariba was studied during 2017. The introduction of O. niloticus on Lake Kariba has been widely associated with the decline in preponderance of indigenous Tilapiines. The aim of this study was to compare reproductive and growth aspects between exotic O. niloticus and two other indigenous tilapiine species. Samples were collected from four sites at Sinazongwe District, Zambia. Specimens were weighed (g), measured in total length (mm), sexed, and ovaries in ripe/ ripe-running stages collected then preserved in 5% formalin solution. Scales were also collected from specimens and used in aging the fish. The von Bertalanffy growth functions (VBGF) for O. andersonii, O. niloticus and C. rendalli revealed intrinsic growth rates (K) of 0.147yr-1, 0.180yr-1 and 0.791yr-1, respectively. The growth performance index (Φ') was highest in C. rendalli (4.98), then O. niloticus (4.58) and least in O. andersonii (4.36). The average observed fecundity for C. rendalli was 5,135 oocytes, ranging between 3,828-6,941oocytes; lower fecundities of 2,923 (1,455) oocytes and 1,650 (934-3,062) oocytes were respectively observed for O. niloticus and O. andersonii. The differences in fecundity were significant, p<0.05, [ANOVA: F (2,18) = 23.80; p=0.000]. Coptodon rendalli exhibited stronger growth and reproductive characteristics than O. niloticus and O. andersonii, respectively.