[SH] NL50 KK on Axx

Prima, $0.25/$0.50 No Limit Hold'em Cash, 6 Players

CO: $97.13 (194.3 bb)
BTN: $66.40 (132.8 bb)
Hero (SB): $57.06 (114.1 bb)
BB: $58.71 (117.4 bb)
UTG: $14.81 (29.6 bb)
MP: $60 (120 bb)

Preflop: Hero is SB with K K
2 folds, CO calls $0.50, BTN raises to $2, Hero raises to $6, BB folds, CO calls $5.50, BTN calls $4

Flop: ($18.50) Q A 8 (3 players)
Hero checks, CO checks, BTN checks

Turn: ($18.50) T (3 players)
Hero checks, CO bets $9.25, BTN folds, Hero calls $9.25

River: ($37) 9 (2 players)
Hero checks, CO bets $18.50, Hero ???

Anon table.

CO is a fish, BTN a TAG on small sample.

Flop? Just cbet (hoping the fish could call with worse), and give up if someone calls?
Turn? As it has been checked around on the flop, I dont think I can fold vs a stab form the fish.
River? Board is ugly, so just fold?