60-65 would be optimal IMHO.
However, I have caught them in 80+ deg. water. 92 deg. surface temp and fishing 10 feet down. This is freshwater fishing in Tennessee. They were up that high for the bait. (Gizzard and Threadfin Shad) At that time of year you are not able to release them due to stress and the warm water ( Although the bite is so wild at that time of the year we could easily fill the boat). So, we get a limit (2 fish) and quit fishing and go have breakfast
Bernzy