Unraveling the Disparity of Carbohydrate Utilization in Farmed Fish: Perspectives From Comparative Pancreatic Islet Biology

ABSTRACT The potential benefits of enhancing the capacity for carbohydrate utilization in farmed fish, particularly in species with pronounced carbohydrate intolerance, are significant from a number of perspectives. In recent decades, a multitude of research initiatives have focused on elucidating the factors that influence carbohydrate utilization in farmed fish, as well as the biological limitations that constrain this process. Despite the substantial progress achieved thus far, a dearth of clarity persists regarding the biological limitations associated with carbohydrate tolerance among various farmed species. Evidence suggests that, as with mammals, pancreatic islet tissues in teleosts act as the regulatory valve in glucose assimilation and metabolism. However, the precise regulatory intricacies remain to be fully elucidated and are the subject of ongoing research endeavors in fish species. The objective of this review is to provide a comprehensive evaluation of extant research gaps in the domain of fish pancreatic islet endocrinology, with the aim of identifying the biological limitations that potentially impede carbohydrate metabolism. Furthermore, it incorporates recent advancements in research on the pancreatic islet biology associated with physiological functions in glucose homeostasis in the zebrafish model and mammalian animals to provide a more comprehensive overview of the future research directions in farmed fish. In addition, we present prospective avenues for inquiry in fish islet biology and concomitant challenges to achieve a more profound comprehension of the fundamental mechanisms that precipitate carbohydrate intolerance in farmed fish. This review is expected to benefit researchers specializing in the study of glucose metabolism in farmed fish species.