I'd lead the turn personally, the 3better has a flush pretty much never because every high card spade spade combo except As
is blocked so if he doesn't have As
he needs to have 3b K9s A9s, 67s, 79s and none of this is very likely, the fish has a pretty wide range and more likely to have overcalled PF with unsuited cards and will have big spade/pair combo's a decent amount. Plus the 3better is likely to pot control
Ax and
Kx now and possibly even TT should he have that hand.
In awkward spots like this I don't like to rely on the fish to behave in a certain way without a solid solid read on his tendencies because letsnot forget most of these people act completely at random, plus if you c/r the fish the reg will hero fold everything he's pot controlling cos its so obv you have a flush whereas he might call a lead with a large chunk of that range.
As played, having said how infrequently the 3better has a flush, he has now made a quite sizable bet into 2 players both of whom can have a bunch of legitimate flushes, so I'd be pretty damn concerned about the situation. i would just call now for sure, OTR we're going to have a rather horrible decision. If it's a brick then i'm going to chk and if he bets I will base my desicion on a) how likely he is to have 3bet suited connecters, specifically 67 or 79 and b) how likely he is to bet AA or KK for value here. I'd call for sure in game but if he's tight like you say he is then I'd defo consider this a great spot for a hero fold cos of how blocked all the smaller flushes are.
if the river is the
or the
then i'd like to call here because I feel he'd PC AA/KK with a fd but at the same time once those cards fall his value range is combinatronically so thin that he prolly just has it lol
Don;t raise the turn ever IMO. if you're going to check call any brick river yuo could consider a river jam as a decent vacuum play, try muddle his head up and call it off with AA/KK/TT cos he'll check a LOT back i think