Do not feed the hedgehog a fish based product or milk. Water is ideal.
I have fed hedgehogs for some thirty or so years and I find, from their
droppings, that beetles are their main source of food. On many
occasions I have seen a slug in the act of eating from the hedgehogs
bowl but when the hedgehog arrives it ignores the slug. However, I
think that they eat very tiny slugs, those which have not long hatched
and they certainly suck lob worms.

Regards,
Emrys Davies.