Effect of stocking density and diet on growth and survival of jipe tilapia (oreochromis jipe) cultured in Hapas at Sagana, Kenya

Abstract

With an ever-increasing global need for sustainable animal protein, agriculturists are turning to aquaculture for an alternative source of protein and revenue. Aquaculture is widely considered as an important component for enhancing food security, income and nutrition. Tilapias are considered as the best species for culture globally and in Kenya, Oreochromis niloticus has shown significant success. However, little is known about the aquaculture potential of Oreochromis jipe. This study sought to assess the culture potential of O. jipe. An 84 days experiment was conducted at Sagana Aquaculture Centre, Kenya, to assess the effect of stocking density and diet on performance of Jipe tilapia (O. jipe) reared in hapas in an earthen pond. It involved a completely randomized design (CRD) in a 3x2 factorial arrangement (3 diets x 2 stocking densities) in 18 (1m x1m) hapas mounted in an 800 m2 earthen pond. The stocking densities were 30 fish/m2 and 45 fish/ m2 combined with 30% CP of both formulated feed (D1) and Ranaan commercial feed (D2) and 35% CP for Sigma commercial feed (D3). Feeding was maintained at 10% of body weight (BW) adjusted after every 14 days of growth. The effects of stocking density and diet were compared on the basis of mean weight and length, weight gain percent, specific growth rate, survival, feed conversion ratio and average water quality parameters and the means of the variables were analyzed using two-way Analysis of Variance (ANOVA) at p<0.05 to test the effects of the two factors (stocking density and diet) on the various aspects of O. jipe growth and survival. Mean separation from ANOVA test was done using Tukey‟s HSD (Honestly significant difference) at p<0.05 to detail any difference among treatments. The best growth in terms of mean length and weight was achieved in D3 irrespective of stocking density. It recorded mean length 7.50±0.19 cm and mean weight of 6.68±0.45 g respectively. Survival was highest on fish fed on D2 (17.00±1.57 No.) whereas stocking density had no significant effect (p>0.05) on O. jipe survival. There was no significant interaction (p>0.05) of the two factors tested on calculated growth performance parameters (mean weight, SGR, percent weight gain, survival rate and FCR) except for mean length, survival and condition factor which were significantly affected (p<0.05). Stocking density and diet had no significant effect (p>0.05) on all the water quality parameters measured. Furthermore, all the water quality parameters were within the recommended ranges for tilapia culture. The results suggest that diet has a marked effect on O. jipe growth and survival. I therefore recommend that the fish should be fed on a high CP diet in the culture systems.