Estimation of dietary magnesium requirements of juvenile tilapia, Oreochromis niloticus × Oreochromis aureus, reared in freshwater and seawater

► Dietary Mg requirements were quantified for tilapia reared in freshwater and seawater. ► Dietary Mg requirement for freshwater-reared tilapia is about 0.2 g Mg/kg diet. ► Dietary Mg beyond 0.025 g Mg kg− 1 is required for tilapia reared in seawater.