Evaluation of the effect of temperature on egg development in an attempt to improve hatching success and fry production in Oreochromis karongae

Abstract

A study was conducted to assess the effect of temperature on egg development in an attempt to improve
hatching success and fry production in Oreochromis karongae. Temperature-dependent development rates
and hatching period for fertilized eggs stripped from O. karongae, a mouth brooder, were determined in a
recirculating system set up in a hatchery at the National Aquaculture Center, Domasi, Malawi. Three
treatments namely; 25, 27 and 29˚C, were replicated thrice in 2-L Macdonald type incubation jars stocked
with 265 fertilized stage 1 eggs of O. karongae, at water flow rate of 0.15 L/s. There was a curvilinear
relationship between temperature and egg development, which was best described by a logarithm
regression function. Hatching period decreased with increase in incubation temperature. The shortest
hatching period was 7.3 days, which was observed at the highest incubation temperature (29°C) while the
longest hatching period was 14.7 days, observed at the lowest temperature (25°C). Hatchability and fry
survival were higher at higher temperatures. The study has, for the first time, ably described O. karongae
egg development rates which suggest that increasing incubation temperature holds the potential to
increase fry production, which is currently a bottleneck.