Trying to do three things at once yesterday, I mistakenly bought the cats tuna flavoured biscuits. It's a funny thing but Scoop and Au like chicken, beef, ocean fish, pilchard, and all sorts of other flavoured biscuits, but they won't touch tuna. And if I try to con them into trying tuna cat food from a tin or pouch, they visibly shudder.
It's not that they don't like real tuna; Scoop and Au will eat tuna intended for human people.
Oddly enough the outdoor cats aren't keen on tuna biscuits either. And as they eat everything put in front of them I'm beginning to wonder if there is something odd about the flavour designed by cat food makers.
Alternatively, they might, as Tom suggested after a few beers, be concerned about dolphin safe tuna.
Either way, it's an odd thing to see cats turn down anything fishy.