As I pointed out in this post, Scratchy is really interested in the smaller members of the family – the fish, the lizard, and – because they're family until they're food - the crickets.
Cricket-Catcher (the lizard/carnivore/jaws-of-death guy) has been thrown off his game somewhat. Til the advent of Scratchy, he's always been the king of the food chain, at least in his tiny reptillian mind. Now, when the large, furry, toothed-and-clawed monster is watching intently through those glass walls, or worse, through the relatively flimsy screen roof, Cricket-Catcher doesn't feel so royal any more. Bill said the lizard looks stressed, and in my opinion, that's not a terrible thing.
And you know, I have to give our lizard credit for the changes he's made. He's learning to look at his position in the food chain, and in the "great circle of life" a bit…differently.