$5 NLHE Full Ring: nut flush facing aggression on paired board

[blueskies]

I made the nut flush on the river, but I get raised by CO who showed no aggression until the board pair. Should I just call or raise? I am probably up against a boat here right?

Full Tilt - $0.02/$0.05 No Limit Hold'em (9 players)
Full Tilt Hand Converter Tool from CardsChat.com

SB Hero: $4.72
BB: $3.92
UTG: $3.43
UTG+1: $4.16
MP: $5.29
MP+1: $3.19
MP+2: $3.45 (sitting out) - Sitting Out
CO: $5.54
BTN: $5.21

Pre-flop: ($0.07) Hero is SB and dealt
5 folds, BTN calls $0.05, Hero calls $0.03, BB checks

Flop: ($0.15) (4 players)
Hero bets $0.10, BB folds, BTN calls $0.10

Turn: ($0.35) (3 players)
Hero bets $0.24, BTN calls $0.24

River: ($0.83) (3 players)
Hero bets $0.40, BTN raises to $1.05 ...

 

[c9h13no3]

I'd just call. There's not many of combos of flushes that are worth a raise (only Ks really) because all the high spades are out. If the board was something like 5s9sTs2c2s then raising the river would make more sense, since there are more possible big spades for our opponent to have.

I also fold preflop (or raise if you really must play this giant ball of reverse implied odds).

 

[badaboombaa]

Bet/fold river imo, he always has a boat here or a straight flush no one raises this river with just Ks and he's never bluffing with that sizing.