CO in this hand was a total fish. He's called most of my preflop raises up to this point. He just seems like an overall bad player. In this hand he has $85, I cover. I've been cutting down on my c-bets because there was one or two other bad players that called way to much. Thoughts?

Poker Room skin
No Limit Holdem Ring game
Blinds: $1/$2
5 players
Converter

Hero is UTG with A K

Pre-flop: (5 players)
Hero raises to $8, CO calls, 3 folds.

Flop: 6 - J - 4 ($19, 2 players)
Hero checks, CO checks.

Turn: 2 ($19, 2 players)
Hero checks, CO bets $8, Hero calls.

River: J ($35, 2 players)
Hero checks, CO bets $12, Hero calls.

Final pot: $59