While worms will eat fish, we generally advise against it as it can get smelly quickly as a wormery is usually not smelly at all. Small quantities of cooked meat, however, are fine.
Try to avoid using acidic foods in quantity such as oranges, lemons, limes and the peel. The worms find acidic conditions uncomfortable. We supply all our wormeries with an anti-acid lime mix which helps to neutralise an acidic environment.
Other than that, pretty much all your cooked and uncooked food waste can be added straight into a wormery, although cutting up thick fibrous waste such as broccoli and cauliflower stalks can be helpful. Fruit peelings, coffee grounds, cooked scraps, potato peelings, bits of cardboard, kitchen paper and vegetable and salad wastes will all work.
Whatever food you put in should be rotting when you put it in so that it can effectively processed by the worms. They'll also love it!