I had a spot yesterday that's both sort of interesting and not at the same time. Playing a 1/2 game on Sky, I don't know anything about villain but suspect they're a fish as they're not playing a full stack.
We m/r button to £4 with

Villain playing £137 to start calls from BB
Flop

Check Check (Fairly obvious I would have thought)
Turn

Check Check (Would usually bet most turns to try and start building a pot but this feels like an odd one as theres still not really much out there to get any sort of value from)
River

Villain bets £4.50 (into £9), we raise to £15.50 they jam £135.
Thoughts on all streets, particularly river appreciated?