First hand: A flop check-minraise is almost always a weak hand, so a push with the nut flush draw is not a bad choice if he's capable of folding weak one pair hands facing this level of strength.

Second hand: This is the fish's favorite flopped set line. I fold to the turn minraise.

Third hand: This might sound weak, but I'd probably just fold to the minraise. You bet out, got raised with a high pair on board, and then a player who checked then calls a substantial bet and raise? I'd expect to see at least J-T from one of these players, and MP could have you crushed with something like 2-2. Also, if you call here, you're unlikely to get much more action if you do in fact have the best hand, but if your hand is not good, you'll be in a position to lose more money on the next two streets. Just get out of the hand early.