If you aren’t checking the water temperature, you’re basically fishing blindfolded, according to an article by Field and Stream. Because trout are cold-blooded, the river dictates their entire mood, metabolism, and menu. Invest a few bucks in a traditional submersible thermometer to get the real story from the bottom of the creek. Slapping a mouse pattern across the surface after dark is a legendary way to trick a giant brown trout. High heat and low oxygen levels cause extreme stress for trout, which is why wildlife agencies implement “hoot owl” fishing restrictions during the dog days of summer.