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.