Oreochromis karongae (Trewavas) is one of the indigenous Tilapias
that exhibit favorable traits for aquaculture in Malawi. However, fingerling
production has been a problem. An experiment was therefore carried out to find
the effect of temperature on oocyte development of the fish. Female O. karongae
were reared under two temperature regimes, room (20.3 ± 0.8°C) and raised
(26.5 ± 0.5°C) for 90 days while changes in gonadosomatic index (GSI) and
oocyte developmental stages were followed every 45 days. Fish samples from the pond
in which experimental fish were collected were used for comparison. Results showed
that raising temperature to 26.5 ± 0.5°C significantly enhanced oocyte
development. Higher GSI (p<0.05) were obtained after 45 and 90 days in fish cultured
in raised temperature (0.817 ± 0.657 and 1.133 ± 0.471 %, respectively)
than those from room temperature (0.057 ± 0.027 and 0.367 ± 0.045 %,
respectively). GSI of fish samples from the pond were not different from that of fish
from room temperature. Relative frequency of mature oocytes was higher (p<0.05) in
fish from raised temperature (60.42 ± 3.63 %) than in fish from room
temperature (1.76 ± 0.84 %) and pond (2.43 ± 1.38 %) after 45 days.
After 90 days, the frequency of mature oocytes in fish from raised temperature was
not different from that in fish from the pond (8.68 ± 2.40 and 10.99 ± 3.41 %
respectively). Fish from room temperature had a low (p<0.05) frequency of mature
oocytes (3.12 ± 2.03 %). The results suggest that O. karongae has the
potential to spawn throughout the year if temperature is manipulated.