Artificial Breeding Protocol and Optimal Breeding Environment for Labeo victorianus (Boulenger, 1901)

Abstract

Broodstock were collected by use of an electro - fisher from four rivers; Mara, Migori, Nyando and Yala and transported to KMFRI Sangoro hatchery for spawning. They were subjected to a 3 x 2 x 4 factorial des ign (3 temperatures x 2 ovaprim dosages x 4 populations) with 72 treatments (3 replicates per treatment) in aquaria flow through system. Each replicate in every population were subjected to 22± 1°C, 26± 1°C and a control (no temperature regulation). Two ovaprim dosages (0.2 and 0.5 mlkg - 1) administered to female brooders. Latency pe riod significantly (p < 0.05) varied among treatments but remained the same among populations. There was no significant difference (p > 0.05) in latency period between the two ovaprim dosages (0. 2 and 0.5 mlKg - 1). However, temperature had a significant (p < 0.05) effect on the spawning time, brooders under 26±1 °C responded at 6 - 8 h, those under 22±1 °C responded at 12 - 18 h and the controls responded at 16 - 18 h. Fecundity significantly (p < 0.05) depended on fish size and river source. Mean fertilization an d hatching rate were both dependent on temperature with temperature of 26±1 °C being the best performer for all populations. Ovaprim dosage had no effect on ovulation. Larval survival was directly dependent on temperature with 26±1 °C having the highest la rval survival (89%), while the control had the least survival (67%) but not significantly different from temperature 22±1 °C (71%). Yolk sac reabsorption was not s ignificantly related to the population source and ovaprim dosage but was directly related to temperature with temperature 26±1 °C having the shortest time (18 - 24 h) post hatching. Results indicate that ovaprim dosage of 0.2 mlKg - 1 and water temperature of 26±1 °C provides the optimal L. victorianus breeding conditions in captivity.