RES are pretty hardy. I know they prefer slightly cooler water temps than bg. But boy are they crummy breeders. They are my favorite sunfish/bluegill, and yet I have so few in my ponds. But I have some big ones, getting to 2 lbs. Of course I would check with my local F and G or hatcheries and fish farms for the best advice as how they would fare in colder climates. I plant them in every single pond I plant. And they are my most requested fish. Why? They tend to get big, almost never overpopulate and stunt, and are great fighters. But after a few years you just don't catch many anymore. I have a pond over 10 years old, that planted equal numbers of them and bg, and today I catch 1 or 2 RES for every 98 or 99 bg. I'm heading there today. Taking out more bg, c and r lmb and res.
