Growth performance of Nile tilapia (Oreochromis niloticus) and Mirror carp (Cyprinus carpio) in Earthen ponds in Kabale and Kanungu Districts, Uganda

Abstract

Deterred investment in aquaculture in the districts of Kanungu and Kabale in Uganda has been attributed to unfounded beliefs that the temperature regime of the region does not favor desired growth of commercially farmed fish. This study examined the effect of water quality including temperature, pH, nitrite, ammonia, chloride, calcium carbonate and carbon dioxide on the growth rates of O. niloticus and C. carpio raised in earthen ponds in Kanungu and Kabale Districts in Uganda in order to generate information needed to guide investment in aquaculture. Water quality parameters and fish average body weight were measured on seven different intervals across the production cycle. Results indicated that water quality parameters for Kabale and Kanungu Districts measured during the seven months of the rearing period were within acceptable ranges for the growth of O niloticus and C carpio. Water temperature was higher in rearing ponds of Kanungu than the case in Kabale at P value of 0.001 which was less than the p critical value of < 0.05. On the other hand, Chloride and calcium carbonate were significantly lower in Kanungu District compared to Kabale at p = 0.002 and p = 0.0001, respectively. Oreochromis niloticus cultured in ponds in Kabale District were heavier (200.5+0.8g) than O. niloticus in Kanungu District at the end of the production cycle (137.7+100.3 g). Similarly, C. carpio in Kabale District were heavier (237.7±100.3g) than that reared in Kanungu District at the end of the production cycle (114.25±94.1 g). However, there was no significant difference in weight gain and specific growth rate for each of the fish species between Districts (p>0.05). The weights attained by the two fish species (O. niloticus and C. carpio) within the seven month production cycle were comparable to that in other agro ecological zones in Uganda. We conclude that temperature range in Kanungu and Kabale district had no influence on the growth performance between the two districts and therefore not a limiting factor for fish culture in the southwestern agro ecological zone. The opportunities to increase production for commercial purposes in the southwestern agro ecological zone should be exploited.