Sweet fish: Fish models for the study of hyperglycemia and diabetes

Fish are good for your health in more ways than you may expect. For one, eating fish is a common dietary recommendation for a healthy diet. However, fish have much more to provide than omega-3 fatty acids to your circulatory system. Some fish species now serve as important and innovative model systems for diabetes research, providing novel and unique advantages compared with classical research models. Not surprisingly, the largest share of diabetes research in fish occurs in the laboratory workhorse among fish, the zebrafish (Danio rerio). Established as a genetic model system to study development, these small cyprinid fish have eventually conquered almost every scientific discipline and, over the past decade, have emerged as an important model system for metabolic diseases, including diabetes mellitus. In this review we highlight the practicability of using zebrafish to study diabetes and hyperglycemia, and summarize some of the recent research and breakthroughs made using this model. Equally exciting is the appearance of another emerging discipline, one that is taking advantage of evolution by studying cases of naturally occurring insulin resistance in fish species. We briefly discuss two such models in this review, namely the rainbow trout (Oncorhynchus mykiss) and the cavefish (Astyanax mexicanus).