It's a simple fact that most game fish bite all 12 months of every year. I've caught largemouth bass in every month, bluegills, crappie, yellow perch, walleye, trout and more, and the only problem traditionally is deciding where they'll be and what they'll strike in a given month. Which isn't as hard as you might think.
Lake Erie walleye, for example, were biting well under the ice this winter, and they'll continue to bite well once the ice goes off, which has either already happened or will shortly. Not many area anglers will seek them in frigid cold water often with equally frigid air temperatures, but if you're serious about the business, like to catch really big walleyes as well as small ones, the early bite is one to exploit.