Developmental studies have indicated that experience is frequently required to produce coordinated agonistic behavior. Learning when to show a threat display could be the proximate mechanism. This paper examines the effects of punishing threat displays with an electric shock. We predicted that shocked fish should decrease their use of threat, but the prediction was not borne out. If anything, the incidence of threat may have increased with punishment, apparently due to an inherent motivational conflict. Constraints against learning not to show threat displays could have been favored by: 1) selection for truthful communication, 2) complexity of aggressive contests, and 3) parallel use of the threat action pattern as a manœvre to deflect bites and minimize damage during painful attacks.