65o 6max HT hu

I would fold.
I think shoving only makes sense if you have a note that villain calls to tight.
I would r/f sometimes in this spot maybe not with 65o because most villains will think we want to induce when minraising at this stackdepth.

Against passive fish you can limp and stab any flop.

This is I believe a minus EV nash shove. It can still be profitable depending on how the opponent is, but question is if it's the most profitable choice. If the opponent never 3bets light, but flats a lot and plays back postflop, I would not raise preflop. If he 3 bets a lot, then raising 65o would be even worse. If he 3bets w strong hands only, but folds the rest-shoving can still be plus ev, but then raising becomes so much better, because the risk:reward ratio is better as we are raise/folding. Just giving you an examples so maybe you figure out what's the best option. Usually fishes are quite call happy preflop, but play very straight-forward in limped pots(no iso-ing loose either), so maybe limp/stabbing here is a good option.

Vs a reg-it depends so much on dynamics. Usually not shoving this as it's minus EV nash shove, not raising either as it will induce most regs. However, like I mentioned, dynamics here is the best advice imo. If you limped a strong hand recently, maybe limping becomes a good option. If he's seen you min-raise inducing with a lot of Ax and other strong hands, you better do the same thing with 65o as you are likely to get a lot of folds. If he is ultra aggro 3-betting loose and iso-ing very loose, folding is best. Shoving will never be a good option vs a reg imo as for one thing your range can be a bit capped and for another, he is likely to call nash or looser, so it makes it clearly minus ev.

Vs a fish-see the first part of the analysis.