No one knows really. Probably just the strong smell. Cold food has less flavor and smell even to people. If it's a cat food tuna, nutritional completeness should not be a problem.

My cats, including the finicky one, really love bacon. It's either the saltines or greasiness, possibly both.

OP here--thanks! Tuna is cat food tuna, and cat is not overweight (although def. not skinny). I will keep rotating. What's with cats and tuna though? Just curious.