Résumé
The demand for sustainable aquaculture feeds has led to the exploration of alternative protein sources, including insect meals.This study investigated the effect of replacing dietary fishmeal (FM) with black soldier fly larvae meal (BSFLM) on thenutritional composition and heavy metal content of fillet tissues from farmed dusky kob (Argyrosomus japonicus) juveniles.Four isonitrogenous, isolipidic, and isocaloric experimental diets were formulated by replacing FM with BSFLM at 0, 33, 66,and 100%. After a 96-day feeding period (starting from 131 ± 0.33 mm/fish standard length), three replicates of an approximately200 g pooled sample of skinless fillets (from five specimens) were collected from each dietary group for analyses of proximatecomposition, amino acids (AAs), fatty acids (FAs), trace elements (iron, zinc, copper, chromium, cobalt, and nickel), andheavy metals (lead, mercury, cadmium, and total arsenic). Proximate composition (moisture, crude fat, crude protein, andash) was determined by oven-drying, Soxhlet extraction, the Dumas method, and furnace incineration, respectively. Aminoacids were measured using high-performance liquid chromatography, and FA were analysed by gas chromatography-massspectrometry following transesterification. Trace elements and heavy metals were quantified using inductively coupled plasma-mass spectrometry. No significant differences (p>0.05) were found in the fillet's proximate composition among fish fed the four diets. While thecontent of most analysed amino acids (histidine, serine, arginine, glycine, aspartic acid, glutamic acid, threonine, alanine,proline, tyrosine, phenylalanine, leucine, lysine, and methionine sulfone) remained unaffected, the essential AA valine wassignificantly lower in fish fed the 100% BSFLM diet compared to the control and 33% BSFLM diets, and isoleucine decreasedat 66% and 100% BSFLM. No significant differences (p>0.05) were observed in the content of FAs such as docosahexaenoicacid and the essential FAs linoleic acid and linolenic acid?except for the non-essential monounsaturated fatty acid palmitoleicacid, which was reduced as BSFLM inclusion increased. Mercury and arsenic concentrations also decreased with higherBSFLM inclusion, whereas trace elements and other heavy metals showed no significant differences.Overall, these findings suggest that BSFLM-based feeds are a viable alternative to FM-based diets from a nutritional standpoint,providing stable key nutrients in the fillet and reducing mercury and arsenic levels, despite modest decreases in certain essentialamino acids at higher inclusion levels.