ShoreBoundOne & catslayer, line size is going to depend upon where you fish & how you fish. Off the bank in the Ohio River 20# is usually fine, from a boat, it's plenty good too. I've gone to 25 & 30# line because we are on a quest to break the IN & KY state record bluecat of 104# caught in 1999.
Fishing high snag areas in smaller rivers, creeks, you probably would want to go with 30# min. up to 50#
Current is going to factor into it also, alot of current in the rocks is going to beat & weaken your line too. That's an advantage fishing from the boat, the line isn't in the rocks as bad.