Mr. Nutmeg clearly can't tell if he should be impressed with Heathcliff or enraged at him.

Impressed: He owns a cat who is smart enough and has the resources to flood the basement and stock it with trout.

Enraged: Where to begin? Heathcliff's "resources" typically begin and end with Mr. Nutmeg's wallet. The credit card bill will surely mention something like an in-basement pool, at which point Mr. Nutmeg will be forced to go on a manhunt for the guy who flooded the basement on the merits of "Meow. #*%&. Meow." His empty basement is now a lake, which means that he has no place to imprison Mrs. Nutmeg or Iggy for disobeying him. Heathcliff is stretching out his favorite pair of goulashes. The plumber feels the need to explain a clearly explainable situation.

Sooner or later, enough will be enough. In this tough economy, one can't afford man made basement lakes, let alone stocking that lake with trout. Money is tight, and Heathcliff is going to have to realize that. Sadly for him, that moment probably won't come until Mr. Nutmeg chucks the fat fucker into the deep fryer.