Oreochromis karongae (Trewavas, 1941) is one of the indigenous Tilapia
species exhibiting favourable traits for aquaculture in Malawi. However, commercial
fingerling production is still a problem. An experiment was carried out to investigate
the effect of raising ambient temperature to 27°C on oocyte development of the
fish. Female O. karongae were reared under two temperature regimes: at room
(20.3 ± 0.8°C) and at raised (26.5 ± 0.5°C) temperature for
90 days. Changes in gonadosomatic index (GSI) and oocyte developmental stages were
determined every 45 days. Fish samples from the pond (22.5 ± 3.4°C) from
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 GSIs (P 0.05) were obtained after 45
and 90 days in fish cultured at elevated temperature (0.82 ± 0.66 and
1.13 ± 0.47%, respectively) than at room temperature (0.06 ± 0.03 and
0.37 ± 0.05 %, respectively). GSI of fish samples from the pond were not
different from that of fish from room temperature. After 45 days, relative frequency
of mature oocytes was higher (P 0.05) in fish from
raised temperature (60.42 ± 3.63%) than in fish from room (1.76 ± 0.84%)
and pond temperature (2.43 ± 1.38%). After 90 days, the frequency of mature
oocytes in fish from raised temperature was not different from pond fish
(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 when the temperature is manipulated.