The giant chestnut was sent off the 1/2 favourite and gave odds-on backers not a moment's worry as he sauntered through the two miles, five furlong contest at the head of affairs.
A superb jump two out saw him take complete command of the race and although old foe Latest Exhibition briefly threatened to close the gap, Monkfish was still effectively on the bridle.
He popped the last and stayed on strongly to the line, rider Paul Townend able to ease him right down for a clear victory.
“The horses are just in fantastic form. What can you say after a performance like that? Paul thought he should be in the next race (Irish Gold Cup),” said Mullins.
“Today I was more impressed than any day. It looks like he might be getting better with each run, it was the ease with which he did it.
“Everything is just so effortless. He just goes down, jumps, gallops. He seems to always be in the right position, he has huge scope – no matter where he is he gets his shoulders off the ground and bends his back.
“Paul never looked worried, he looked like he was a lead horse for the others, turning for home.
“It’s as easy watching him as any horse, he just does everything so easily. I presume that (Festival Novices’ Chase) is next, but we’ll enjoy today."
Townend said: “All I had to do was sit there and steer him to be honest. He locked eyes on every fence and took them on, the loose horse took me on and set him alight a little bit, but I wasn’t worried because he is just a very good horse.
“The feel he gives me, he isn’t a plodder and has a little bit of class.”
Sky Bet reacted by making the winner 5/4 for the Festival Novices' Chase at Cheltenham and the firm's Michael Shinners said: "Monkfish seems to be getting better and better with experience over fences and continues Willie Mullins' remarkable run of form at Leopardstown. It'll take a serious performance to lower his colours in the three-miler at the Festival."
