Taurine improves the performance of white grouper juveniles (Epinephelus Aeneus) fed a reduced fish meal diet

• Taurine supplementation significantly improved growth in grouper juveniles fed a fish meal-reduced diet.
• Thermal growth gradient suggests effective temperature for growth in grouper juveniles.
• Indirect evidence for a taurine mediated hypocholesterolemic effect in the white grouper liver.
• Fatty acids are preferentially assimilated into the eye tissue compared to muscle and liver tissue.

White grouper F1 juveniles (approximately 19 g), originating from eggs spawned at the National Center for Mariculture (NCM) in Eilat, Israel, were stocked (26 fish tank− 1) in twelve 1000 l conical tanks in an open system using filtered (10 μm) ambient sea water (40‰). Three reduced fish meal (35% of protein), pelleted (1.6 mm) diets, that were similar in protein (51.8%), lipid (12.5%), moisture (10.1%) and caloric (4.8 kcal) content but significantly (P < 0.05) differed in their taurine level (2, 11.2, 22.4 mg g− 1 DW diet) were fed to the fish at 3.0–1.6% of tank biomass (appetite decreased with sea water temperature) for 12 weeks where each dietary treatment was tested in 4 replicate tanks. Supplementing taurine in the IOLR reduced fish meal grow out diet significantly improved wet weight gain and thermal growth coefficient (TGC) in juvenile white grouper, which was maximum at 22.7 °C under the experimental conditions. There was a dietary taurine dose dependent response on accumulation of this nutrient in various tissues, where levels can be ranked as muscles > liver > eyes. The decrease in liver total lipid and its constituent fatty acids with increased dietary taurine suggested that this nutrient is exerting a hypocholesterolemic effect resulting in the higher production of bile salts that led to significantly increased levels of total lipid and the fatty acids of all lipid classes in the eyes. In contrast, taurine appears to have had little effect on lipid stores in the muscle of grouper but may have contributed to muscle function.Statement of relevanceThe results of the present manuscript contribute to the commercial rearing of the white grouper in captivity in terms of taurine supplementation and an effective temperature for good growth. In addition, this manuscript expands our knowledge of the effect of dietary taurine on fatty acid metabolism.