No significant differences were noted between responses of rainbow trout Oncorhynchus mykiss facial and glossopharyngeal nerves to 15 amino acids. Nine of these amino acids tested at 10 −2 M were stimulatory, whereas only two tested at 10 −3 M were effective gustatory stimuli. For both nerve systems, ≤10 −3 M L‐proline was the most stimulatory amino acid, with an estimated threshold of 10 −7 M; however, L‐α‐amino‐β‐guanidino‐p...