Pre: I like three betting and I like your sizing.

Flop: I think when we have the initiative here we can fire once here. Definitely no need to go big with this bet so again, I like your sizing.

Turn: K is actually a great card for us, we pick up a guthot to the nuts and a ton of his Kx combos are blocked so I actually like betting this turn and betting on the larger side now to apply maximum pressure on his single non-king pair hands/fold out his flush draws that have a TON of equity against our unpaired hand. Betting somewhere in the region of .65c seems good to me here.

River: As played, checking back. If we had bet as I suggested in the above street, I would also be checking back. We are still ahead of some of his flush draws so our hand has some marginal showdown value and we are very unlikely to be getting Jx to fold here so betting does not make much sense to me.

Turn is definitely close but I sort of disagree that it's a bet. If this player's a fish as OP thinks, he's holding on with most of his range most of the time. The only stuff he might fold are hands like 99/TT but I wouldn't even bank on that at 2nl, and anyway that's a small portion compared to the Jx and draws that he'll call again with. Also, and this is more general, but I find people fold to double-barrels far less in 3bet pots than single-raised ones, which is a problem for us given how expensive it is.

Close though, don't hate double-barreling, just think at this level it's kind of marginal.

Pre looks perfect

I don't expect a massive amount of folds c betting this flop, but we have two overcards and a backdoor nut flush draw givingus plenty of favourable turn cards to barrel.

I like betting the turn here. I would expect 8x to be folding a lot. Plus our Q out may be good and we have the additional straight outs.

As played once you check the turn I wouldn't try bluffing the river, you'll just get snapped off too frequently.