Goldfish were trained to perform an operant in response in order to obtain food, thereby allowing the food intake to be accurately determined. The normal daily food intake was established for each fish before it was given a sham operation or bilateral hypothalamic lesions. It was then observed over a period of up to 60 days. Lesions of the lateral areas of the hypothalamus were found to cause cessations of operant feeding of up to 60 days duration, and cessations of feeding on manually presented food of up to 35 days. Lesions of the anterior-medial areas were followed by cessationsof operant feeding of up to 26 days. The post-lesioning food intake of fish lesioned in the posterior-medial area was similar to that of the control fish. No increases in operant feeding were observed after lesioning. The results are considered to be consistent with a genuine aphagia induced by lesions of the lateral hypothalamus.