High-quality live food is essential for reducing the frequent high mortality of newly hatched fat snook (Centropomus parallelus) larvae in hatcheries. Copepods, a rich nutrition source, cultivated with the microalgae Chaetoceros muelleri and Isochrysis galbana, were evaluated as food for 0–14-day-old larvae. Two experiments were performed using nine 50-L tanks stocked with 2500 embryonated fat snook eggs. Three different dietary (treatments) were tested in triplicate: Experiment 1, Treatment 1 (Control), using rotifers Brachionus rotundiformis (20 mL− 1); Treatment 2 (Copepod), larvae were fed with Acartia tonsa (nauplii and copepodits, 0.1 mL− 1); and Treatment 3 (Mixed), larvae were fed with A. tonsa (0.05 mL− 1) and rotifers (10 mL− 1). In Experiment 2 to increase the density of live food, food organisms and the phytoplankton were introduced into the experimental tanks with the embryonated eggs and were stocked: Treatment 1, 20 rotifers mL− 1; Treatment 2, 0.5 copepods mL− 1; and Treatment 3, 10 rotifers mL− 1 and 0.25 copepods mL− 1. In Experiment 1, the Mixed Treatment increased significantly the survival rate (16.0% ± 7.5%) and mean larval weight (0.84 ± 0.05 mg) in relation to the other treatments. In Experiment 2, we observed significant improvements in larval notochord flexion in the Copepod and Mixed Treatment. The essential fatty acid profile of fat snook eggs had a DHA:EPA:ARA ratio of 11.4:2.4:1.0 while larvae in the Mixed and Copepods Treatments had ratios of 2.5:1.9:1.0 and 5.5:1.9:1.0, respectively. We conclude that the survival, development and the relationship between the major fatty acids were improved in treatments with copepods.