1/3, 275-300 effective, Fish is a reg who never folds to Hero's PFR and flop cbets with TP type hands because he knows Hero cbets 100% but will give up to turn/river aggression if he doesn't have good equity, has bluffcaught Hero multiple times in big pots including river shoves.
Fish limps UTG
Hero raises to $18 UTG+2 with A
K
Another caller
Fish calls
Flop (55): A63cdd
Fish checks, Hero bets 45, fold, Fish calls
Turn (145): 9d
Fish checks, Hero checks
River (145): 7d
Fish checks, Hero checks
Line check please