This study investigated the replacement of fish meal (FM) with fermented soybean meal (SM) and mustard oil cake (MOC) in the diet of Climbing Perch. Given their availability, rich amino acid profiles, low cost, and sustainable nature, plant protein sources are valuable in aquafeed. However, anti-nutritional factors (ANFs), toxic compounds, and high fiber content can reduce their nutritional value and digestibility, negatively affecting fish performance. Fermentation by beneficial microorganisms such as bacteria, yeast, and fungi has been reported to enhance the nutritional quality of feed ingredients and provide probiotic health benefits to fish.
A 60-day feeding trial was conducted using five iso-proteinous (38%) and iso-lipidic diets, where equal proportions of fermented Mustard Oil Cake (FMOC) and Fermented Soyabean Meal (FSM) were incorporated at 15%, 20%, 25%, and 30% to replace FM protein. A control diet was prepared with 15% non-fermented SM and MOC (Table 1). A total of 300 fish (4 g) were randomly distributed (20 fish/tank) into 15, 100-L aquariums as triplicates and fed twice daily at satiation. After the growth trial, fish growth performances, feed utilization, whole body nutrient compositions and hematological parameters were assessed. Results showed significantly higher growth in fish fed the D2 diet, followed by D3 and D1; D4 and D5 diet groups showed significantly lower growth performance (Table 2). Feed utilization performance parameters were not significantly different among diet groups D1, D2 and D3; D4 and D5 groups showed significantly lower performance. Total cholesterol, triglyceride and total protein content was significantly higher in fish fed D2 diet compared to other treatments. Significantly lower whole-body protein, lipid and ash content were observed in D5 diet compared to other treatments. Fish fed D1 to D4 diets showed significantly lower whole body moisture content compared to D5. Most of whole-body amino acid content was significantly higher in fish fed D1 to D4 diets compared to D5 diet. The findings indicate that 20% of fermented SM and MOC can be included in the dietary formulation of climbing perch, which combined 35.2% of FM in the formulation without negatively impacting the growth and health performance of this species.