Scombroid poisoning is described in the literature as a toxic poisonin
g caused by ingestion of certain dark meat fish undergoing bacterial d
ecomposition. Poisoning results from the ingestion of a heat-stable to
xin. We describe the case of a man who presented to the emergency depa
rtment several hours after eating tuna steak with evidence of scombroi
d poisoning that was associated with loss of vision and atrial tachyca
rdia with block. All signs and symptoms resolved after treatment for s
combroid poisoning.