I've had both grass and red fin pickerels for years. Their "personalities" aren't always the same.
My current red fin was bought, online from an Aquaculturist in Florida, when finger-length, many years ago. He's (?) now 12 inches, last time I measured. His life-long tank mate is a female bluegill caught wild at 2", but now somewhere around 10 inches. (She's the only survivor of about 6 mixed sunfish that fought endlessly.)
They are currently reside in a 215 gal., well planted tank. They hang together, side by side, very often. You'd think they were best friends. (Really)
The pickerel started off eating rosies, then goldfish. He's always only eaten live fish. (He once spit one out, now dead, and then wouldn't touch it.) The bluegill eats fresh freeze-dried krill (not soggy, please.)
Luckily, I have turtles in another tank that eat anything these guys won't.
When these guys are gone, I won't hesitate to replace them with the same species.