Rural Cage Aquaculture in Ox-bow Lakes of Zambezi Plains

The experiment was conducted in Zambezi district in Chiwano ox-bow Lake to investigate the performance of cage aquaculture in the ox-bow lakes of Zambezi plains during the cold dry season for five months. A fish cage of 4m long by 2m wide and 2m deep was constructed and put in Chiwano ox-bow Lake. Oreochromis andersonii an indigenous cichlid species in the Zambezi River was stocked in the cage made out of local materials that included bamboos and timber. The cage was stocked with 1,800 fingerlings, at the stocking rate of 120fish/m 3 . Feed was formulated using locally available ingredients that included; fish waste, maize bran and cassava meal. In the first two months, the fish was fed 5% of the total biomass by 3 times per day and 3% of the total biomass by 3 times a day in the last three months. The fish was fed by hand through broadcasting the feed on the water surface in the cage. Physico-chemical parameters of the water such as dissolved oxygen, temperature, pH and ammonia were measured using chemical kits. The mortalities were observed and recorded daily from the time of stocking the fish. Thirty (30) fish were sampled randomly and returned to the cage every month and their standard lengths and weights recorded for five months. The results showed high survival rate of 84.3% and positive specific growth rate of 6.74%. The water quality in the lake had an average pH value of 7.5, average temperatures were above 20°C, the dissolved oxygen (DO) averaged at about 5.3ppm and ammonium nitrogen averaged at 0.013mg.dm -3 . It was concluded that though the performance of cage aquaculture in the ox-bow Lakes of Zambezi plains through the cold dry season was low, the growth rate of the fish was positive.