From the Iowa DNR: What's The Best Time of Day to Catch Fish? Anglers may argue until they’re blue in the gills about the best bait to use in procurement of our fine, finned friends. But most are in agreement that, above all else, weather distinguishes a good day of fishing from a bad one. Not unlike most humans, weather conditions affect the behavior of our aquatic acquaintances. In addition to the logistical challenges of casting or boating in wind or rain, and population migrations revolving around water temperature and barometric pressure, prepared piscators must be meticulously mindful of natural light conditions. According to DNR fisheries bureau chief Joe Larscheid, fish tend to be most active during crepuscular times (dawn or dusk), which is when fish are feeding and subsequently when fishing is best. As light levels in the water diminish, prey fish tend to stray from cover to feed and predators follow their prey. In addition, and as Larscheid confirms, “Some predators have evolved special ways to exploit predation in low light conditions. For instance, walleyes have evolved a special light gathering layer in their eyes called a tapetum lucidum, which enable them to see well in low light conditions giving them an advantage over prey fish.” This is why walleye fishing is always best during low light conditions.