Argopecten nucleus and Nodipecten nodosus are two Caribbean scallops occurring in Colombia, which have recently been selected for artificial culture based on their high commercial value. As part of an effort to develop culture technology for these species, we studied the effects of food concentration and temperature on feeding rates (filtration, ingestion, and absorption), oxygen consumption, ammonium excretion and scope for growth in adults of the two scallop species. We tested the effects of four concentrations of the microalga Isochrysis galbana (10, 20, 40 and 60 cells μL⁻¹) at three water temperatures (20, 25 and 28°C), at a constant salinity of 36‰. The results showed that increases in food concentration induced increases in feeding rate, oxygen consumption and growth potential, but at values of 60 cells μL⁻¹ these variables decreased, indicating saturation of the digestive tract. The excretion rate increased at low food concentrations, particularly at the middle (25°C) and/or at the highest temperature tested (28°C). This suggested utilization of endogenous proteins as a supplementary energy source under these conditions. The increase in temperature had no significant effect on the feeding variables or on the scope for growth of A. nucleus, but raised the N. nodosus ones. All the physiological rates for the two species were similar except for oxygen consumption, which was greater in N. nodosus than in A. nucleus. Using values obtained for the algae concentrations, which produced the greatest growth potential, the optimal value for I. galbana for both the scallops was 40 cells μL⁻¹, whereas the optimal temperature for N. nodosus was 25°C. There was no single optimal temperature for A. nucleus, which functioned equally well at between 20°C and 28°C.