“He’s apparently a very picky cat, and if I serve him anything other than fresh salmon he flies into a tantrum”…
Well, he is really going to freak out since R’ Gavornlik, shlita, just paskined that the tolayim present in virtually all salmon are totallly asur in accordance with the holding of the Shulchan Aruch in Yoreh Deah (84:16). Recent studies have shown that in salmon, the tolayim migrate from the viscera to the flesh and skin. There are still some excellent varieties of dried kitty- kibble with outstanding chassideshe hashgacha that he may learn to love over time versus a painful death from hunger.