On-farm growth performance of different strains of tilapia, Oreochromis niloticus reared in earthen ponds

The growth of aquaculture sector in Kenya has been anchored on farmed Nile tilapia Oreochromis niloticus. Different strains of the species exist in Kenya with unknown quality due to lack of stock improvement programmes coupled by variations in breeding and management practices in different hatcheries. The seeds supplied to farmers have not exhibited good performance and resilience to changing climate. There is need to validate the quality of strains supplied to fish farmers in Kenya. This study sought to compare the growth performance of three strains of farmed Nile tilapia; Sagana strain (SAG-F8) produced through selective breeding, super YY strain (KAM-YY) from Kamuthanga fish farm and the local strain (LOC-T) obtained from Siaya County. The fish were stocked in fertilised earthen ponds measuring 300 m(2) in triplicates at 3 fish/m(2). The fish were fed on 35% crude protein diet for 180 days at Bukani Aquapark located in Busia County, Kenya. There was no significant difference in mean weight gain (MWG) between SAG-F8 and LOC-T strain exhibiting 159.786 +/- 6.76 g and 158.623 +/- 4.67 g, respectively. However, under similar conditions, the KAM-YY strain had a significantly lower MWG (131.74 +/- 4.75 g) compared to the two strains. Food conversion ratio (FCR), specific growth rate (SGR) did not demonstrate any significant difference among the different strains. The body protein content in the SAG-F8 fish strain was higher (65.40 +/- 0.20%) followed by LOC-T strain (61.23 +/- 2.34%) and lastly KAM-YY strain had the lowest (60.37 +/- 0.89%). In this study, the impact of genetic improvement has been demonstrated to influence growth and feed efficiency as well as body composition. These improved strains will substantially increase fish production and productivity, hence, a positive impact on the fish farmers' livelihoods when supplied to the farmers and seed multipliers.