Arginine Supplementation for Juvenile Florida Pompano ( Trachinotus carolinus ) in Practical Plant‐Based Diets

This study aimed to evaluate the effects of dietary arginine (Arg) supplementation on juvenile Florida pompano ( Trachinotus carolinus ). Diet formulation was based on the Arg requirement reported for golden pompano ( Trachinotus ovatus ), 2.73% of diet. Eight isonitrogenous (40% crude protein) and isolipidic (8% crude lipid) diets were formulated with varying levels of L‐arginine supplementation (0%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.65%), resulting in dietary Arg concentrations ranging from 2.32% to 2.94% of the dry diet (5.66% to 6.95% of dietary protein). Five replicate groups of 12 juvenile pompano at an initial weight of 11.06 ± 0.27 g (mean ± standard deviation) were fed these experimental diets for 12 weeks in a recirculating aquaculture system. Growth performance parameters, including final weight (53.06–59.96 g), percentage weight gain (381%–442%), feed conversion ratio (1.64–1.80), thermal‐unit growth coefficient (0.58–0.68), survival (96.67%–100%), and apparent net protein retention (24.48%–26.79%), showed no significant differences among treatments. Whole‐body proximate composition, amino acid profiles, and serum biochemical parameters remained unaffected by different dietary Arg levels. Gene expression analysis of hepatic ( ppara , igf1 , tor , mnsod ) and intestinal ( ocln , zo1 , lyz , il8 ) target genes similarly revealed no significant treatment effects, indicating that hepatic metabolic regulation, intestinal barrier integrity, and mucosal immune status were maintained at the tested Arg range. Under these conditions, results suggest that the dietary Arg requirement of juvenile Florida pompano is ≤2.32% of diet (≤5.66% of dietary protein), and that conventional animal and plant protein ingredients supply adequate Arg to support growth performance, feed efficiency, and normal physiological function. Thus, Arg supplementation may not be required even in low‐animal‐protein diets, supporting more cost‐effective feed formulation.