Impact of defatted black soldier fly larvae meal on growth, feed utilisation, and fillet quality in freshwater-reared Asian seabass

Abstract Asian seabass ( Lates calcarifer ) is a commercially important fish in Asian countries. The feed formulation for Asian seabass relies significantly on the utilisation of fish meal (FM) as the primary protein source. However, given the challenges posed by its limited availability and elevated cost, there is a need to explore potential alternatives to FM. This study aims to evaluate the possibilities of using defatted black soldier fly larvae meal (DBSFLM) as FM alternative in the diet of Asian seabass reared in freshwater. Three isonitrogenous (45%), isolipidic (13%), and isoenergetic (400 kcal/100 g) experimental diets were prepared using graded replacement levels of FM by DBSFLM: 0% (control), 20% (D20), and 40% (D40). Experimental diets were fed to triplicate groups of 15 Asian seabass fingerlings with an initial body weight of 9.44 ± 0.02 g twice per day until satiation. After a 7-week feeding trial, fish fed the control diet showed significantly better growth performance and feed utilisation ( ) compared to those fed with D20 and D40, indicating reduced efficiency in utilising DBSFLM. However, no significant differences ( ) were observed in condition factor, biological indices, haematocrit levels, survival rate, or fillet yield. Meanwhile, Asian seabass fed with the D20 exhibited increased levels of metallic and muddy flavour in the fillet, contributing to a distinctive taste profile. Overall, replacing dietary FM with DBSFLM at levels of 20% and 40% resulted in compromised growth performance, feed utilisation, and fillet sensory qualities in Asian seabass raised in freshwater.