I can't offer any comment on the food, but ...
 adult mamals mostly can't digest milk properly - it may give them
the runs
 you didn't say what kind of fish - cats do have their preferences:
most will eat top-of-the-line human tuna (in water, not oil), though
some will just lap up the broth; in my experience, other canned fish
and fish products are a waste of money.

I can't answer that, but I was told you shouldn't give a cat cows milk
anyway as it's not good for them.

Marcia