Growth performances, physiological and antioxidant responses of Asian seabass to fractionated and non-fractionated black soldier fly larvae meal

Abstract

The continuous increase in the demand for fishmeal, a major ingredient in the aquafeed industry, has led to the adoption of black soldier fly larvae (BSFL) as a potential fishmeal protein replacement. However, chitin in the BSFL exoskeleton may negatively impact fish performance. This study analysed the impacts of fractionated BSFL (F-BSFL) and non-fractionated BSFL (NF-BSFL) as fishmeal replacements on the growth performance, haematological analysis, metabolic and antioxidant enzymes activities of Asian seabass, Lates calcarifer . Fish were fed twice daily to apparent satiation for 60 days while maintaining optimum water quality parameters. Results revealed that F-BSFL significantly improved weight gain, specific growth rate and protein efficiency ratio compared to NF-BSFL, though both were comparable to the control. Although feed intake was similar across treatments, feed conversion ratios were significantly better for F-BSFL and control than for NF-BSFL; however, survival was highest in control-fed fish. Blood glucose and haematocrit generally displayed an increasing trend, with lower values for the control diet, followed by F-BSFL and NF-BSFL, while total serum protein, lysozyme and liver glutamic-oxaloacetic transaminase showed an inverse trend. Antioxidant enzyme activities (glutathione reductase, glutathione peroxidase and glutathione S-transferase) were highest in control-fed fish, followed by F-BSFL and NF-BSFL, while other antioxidants remained similar. Overall, the study highlights fractionation as an effective approach to reduce chitin in BSFL, resulting in improved growth performance, physiological and antioxidant responses towards advancing its application as a sustainable fishmeal substitute for Asian seabass.