CONDITION FACTOR OF NILE TILAPIA, OREOCHROMIS NILOTICUSFRY UNDER THE INFLUENCE OF DIFFERENT PROTEIN LEVELS IN A BIOFLOC SYSTEM

The study was conducted at Kenya Marine Fisheries Research Institute (KMFRI), Sangoro Station, Kenya to compare the growth perfomance of Oreochromis niloticusfry under different protein levels in a biofloc system using weight-length regression models and Fulton`s condition factor (K). Fry of initial mean weight 0.07 ± 0.03 g and length 1.30 ± 0.24 cm were randomly stocked in 18 aquarium tanks with capacity of 50 litres at stocking density of one fish Litre-1. The experiment was set in a greenhouse under controlled temperature and dissolved oxygen conditions using aerators and thermostat heaters. The biofloc used glucose and molasses as carbon sources which were assigned at 22%, 27% and 35% crude protein levels randomly to the aquaria. The fish were fed on their daily ration twice a day at 5% body weight for 14 weeks. Physicochemical parameters were recorded daily using a multiparameter meter and water samples collected before fish sampling for nutrient analysis. A sample of 30 fish per tank were used for taking body weight and total length measurements using an electronic balance and a measuring board respectively. Fry in all treatments exhibited allometric growth with b coefficient varying between 2.54 and 2.66. Average Fultons condition factor ranged between 1.77-1.84 with no significant difference (P>0.05)among the protein levels and the bioflocs. The condition factor showed both carbon sources were suitable for use in the biofloc system and hence replacement of higher protein level (35%) with lower protein level (22%) to reduce the production cost is a feasible application of the biofloc system in fish farming.