We finaly found something other than fancy feast that he will eat. Straight tune from the can. I don't know if we want to keep that up though.
Be careful if it is tuna packed in vegetable oil -- the oil interferes with vitamin uptake (can't remember which - D or E or ?) in the gut and can cause deficiency. Veggie oil is a no no for cats, even if they love margarine they shouldn't have it.