A 4 × 3 factorial experiment was conducted for two weeks to determine the effects of ration level ranging from starvation to satiation and water temperature at 21, 27 and 33 °C on growth, fecal production, nitrogenous excretion and energy budget of 10-g-size cobia in this study. Over the temperature range, 21–33 °C, maximal ration ( R max, % per day), optimal ration ( R opt, % per day) and maintenance ration ( R maint, % per day) all increased with temperature ( T, °C), described as a quadratic equation R max = − 0.046 T 2 + 2.906 T − 35.97 ( R 2 = 0.989), a simple equation R opt = − 0.533 T − 8.001 ( R 2 = 0.993), and a quadratic equation R maint = 0.028 T 2 − 1.350 T − 17.18 ( R 2 = 1), respectively. Both fecal production ( f, mg g − 1 d − 1 ) and nitrogenous excretion ( u, mg g − 1 d − 1 ) were affected significantly by ration and temperature and increased as ration and temperature increased. Feed absorption efficiency (FAE, %) varied small over the whole ration and temperature ranges though the effects of ration and temperature were significant in some data. Juvenile cobia grew fastest at 33 °C when fed at satiation but the growth rate was equal or better at 27 °C when food was restricted, whereas the fish showed overall significant lower growth rates at 21 °C except for the starved treatment. Among three temperatures specific growth rate in wet weight (SGR w, % per day), dry weight (SGR d, % per day), protein (SGR p, % per day) and energy (SGR e, % per day) all increased with ration, showing decelerating growth–ration relationships described as logarithmical equations at 27 and 21 °C and a linear growth–ration relationship described as a simple equation at 33 °C. Apart from starvation ration with a negative linear growth–temperature relationship growth all increased with temperature, described as quadric functions. Two-way ANOVA showed that ration and temperature had an interaction on growth. By using multiple regression analysis the relationships between specific growth rate (SGR, % per day) and ration level (RL, % per day) as well as temperature ( T) took the forms: SGR w = − 11.97 + 1.23ln(RL + 1) + 0.91 T − 0.02 T 2 + 0.16 Tln(RL + 1) ( R 2 = 0.962), SGR d = − 17.04 + 0.72ln(RL + 1) + 1.11 T − 0.02T 2 + 0.12 Tln(RL + 1) ( R 2 = 0.968), SGR p = − 18.25 + 0.20ln(RL + 1) + 1.28 T − 0.03 T 2 + 0.15 Tln(RL + 1) ( R 2 = 0.972) and SGR e = − 20.83 + 0.85ln(RL + 1) + 1.40 T − 0.03 T 2 + 0.15 Tln(RL + 1) ( R 2 = 0.969). Feed conversion efficiency in wet weight (FCE w, %), dry weight (FCE d, %), protein (FCE p, %) and energy (FCE e, %) at 27 and 33 °C was much higher than that at 21 °C, and the maximal FCE occurred at sub-satiation (i..e. feeding group 3) and 27 °C. All the relationships between FCE and temperature were described as quadric equations. Energy budgets of juvenile cobia at satiation ration were: 100 C = 7.0 F + 7.7 U + 69.0 R + 16.4 G (or 100 A = 81 R + 19 G) at 33 °C, 100 C = 6.8 F + 7.9 U + 68.0 R + 17.3 G (or 100 A = 80 R + 20 G) at 27 °C and 100 C = 6.3 F + 8.4 U + 77.2 R + 8.2 G (or 100 A = 90 R + 10 G) at 21 °C, where C is food energy, A is assimilated energy, F is feces energy, U is excretion energy, R is metabolism energy and G is growth energy.