Technical Abstract: The overall goal of our research is to develop fish with superior growth, and feed efficiency attributes. Feed intake is integral to these characters. Over the last several years we have been working with channel catfish, Ictalurus punctatus, in two directions tied to feed intake regulation. One direction has been to identify genes functioning as physiological regulators of feed intake, and the other has been to measure and characterize the genetic variation in feed intake within and among distinct catfish populations which reveal a wide range in feeding response. The goals are to uncover the genetic basis of physiological variation, to understand the genes and interactions that produce the phenotypic differences observed and to exploit these differences in a selective breeding program. To investigate the links between genetic variation and physiological variation, differences in voluntary feed consumption were documented in two strains of channel catfish. Treatment with orexigenic and anorexigenic compounds affected both strains similarly, through temperature treatment affected the strains differently with respect to feed efficiency. Variation in feed intake among families suggested that approximately 40% of the variation in feed intake is due to genetic sources. Future work aimed at identifying the specific genes responsible for this variation is discussed.