This study was designed to analyze the influence of certain chemical substances on the feeding behavior of juvenile common snook. The following chemicals were tested: L-alanine, L-leucine, L-isoleucine, L-glutamic acid, glycine, L-proline, L-histidine, L-serine, L-lysine, L-arginine, inosine-5-triphosphate, and uridine. Feeding responses were studied in tanks containing one or two fish. The substances were placed in pellets made of agar, at a concentration of 0.01 M. The chemicals found to act as attractants were: uridine, L-isoleucine, and inosine with one fish; and those plus glycine, L-proline, L-arginine, L-leucine, and L-glutamic acid with two fish. The feeding responses were stronger with two fish, indicating that the number of fish had an influence on feeding behavior.