Evaluation of weaning diets for sustainable indoor largemouth bass (Micropterus salmoides) larviculture

<br /><br />This research evaluated the suitability of commercially available larval feeds, Otohime B2 (OB2), Aller Infa (AI), and Aqua Start (AS), and one Experimental Feed (EF), for the weaning of largemouth bass (<i>Micropterus salmoides</i>), LMB. Feeds were presented with various ω-3 fatty acid levels/bioavailability (high in OB2 and AI), fat percentage (high in OB2 and AS), free amino acid and short peptide (FAA + SP) levels (high in OB2), and various soluble protein (SPR) levels (high in AS and EF). Fish were co-fed <i>Artemia</i> plus OB2 from the 19^th to 22^nd day post-hatching (DPH), then <i>Artemia</i> in addition to one of the four above diets for seven days, with complete <i>Artemia</i> removal on the 30^th DPH. Fish were sampled on the 32^nd DPH. Morphometry, digestive enzyme activities, hormonal status, skeleton, muscle development, and potentially pathogenic <i>Flavobacterium</i> spp. levels were estimated. Survival was high (96% or more) in all the weaning regimes. Weaning to OB2 was linked to a fast fish growth rate (14.29%/day), while both OB2 and AI supported the skeleton development. Weight gain correlated with total fat, ash levels, free amino acids, and short peptide levels in the diet. Larvae weaned to soluble protein-rich AS and EF showed the lowest fish weight gain and skeleton development, and lower growth of potentially pathogenic <i>Flavobacterium</i> spp. This research suggests that the weaning diets for largemouth bass should have a balanced protein content and quality while allowing for the inclusion of fewer marine ingredients.