Don't use a food can then.. Try lining the trap with newspaper and dropping pieces of fish from the front (small pieces) to the back of the trap (larger pile of fish). If he enjoys the fish, he will walk further and further in to the trap to get to the big pile at the back of the trap. He won't even notice how far back he is until it is too late.. Then he will get caught! Also, sardines are excellent for catching hard to trap cats. They smell awful and are really slimy, but the cats love 'em!