 I personally don't like to fish them after about 74 to 75. 74 is my very top end, and even then it's getting a little iffy. So once you get to that mid-70s and over, give those muskies a break, and if you're not familiar with why that reasoning is, is a fish that big gets stressed out while you're fighting that fish in, and the hotter that water is, the more stressed out that fish is, and the least