Growth performance of genetically improved farmed tilapia (Oreochromis niloticus) fed diets containing local and imported fish meals in the Saurashtra region

Abstract

The present study evaluated the growth performance, feed utilization, and physiological responses of genetically improved farmed tilapia (GIFT; Oreochromis niloticus) fed diets containing imported and locally manufactured fish meals in the Saurashtra region of Gujarat. Six iso-nitrogenous experimental diets were formulated with graded inclusion levels (15%, 25%, and 35%) of imported fish meal (IF15, IF25, IF35) or locally produced fish meal (LF15, LF25, LF35) and fed to male GIFT fingerlings (initial weight 5.4 g) for 84 days under controlled tank conditions. Growth performance, feed conversion ratio (FCR), protein efficiency ratio (PER), somatic indices, hematological parameters, metabolic oxygen consumption, and water quality were assessed. Fish fed the IF35 diet exhibited the highest final body weight (99.4 g), daily weight gain (1.07 g day⁻¹), and specific growth rate (4.62% day⁻¹), along with improved Food Conversion Ratio (1.62). Comparable growth and feed efficiency were observed in fish fed LF15 and LF25 diets, indicating effective utilization of locally manufactured fish meal at moderate inclusion levels. Haematocrit values and somatic indices increased with higher fish meal inclusion, while metabolic oxygen consumption remained within acceptable physiological limits. Survival was 100% across all treatments, and water quality parameters remained optimal throughout the experiment. Overall, the results demonstrate that locally manufactured fish meal can partially replace imported fish meal in GIFT tilapia diets without compromising growth performance or physiological health, offering a cost-effective and sustainable alternative for tilapia farming in the Saurashtra region, Gujarat.