It was previously observed that solid-state fermentation (SSF) with Aspergillus ibericus increased brewer's spent grain (BSG) protein content (21%) while reducing lipid (49%), cellulose (30%), hemicellulose (34%), and lignin (7.3%) contents. This study evaluated the potential of fermented BSG (BSG-SSF) as a novel feed ingredient for meagre (Argyrosomus regius) juveniles by evaluating growth performance, digesti...