Id also try and get all the dirt and such out of them before you feed. Otherwise it can foul your water up. I usually just pinch one side and run my fingers down to the other to get all of the dirt out.
Put the worms in damp shredded or crumpled up newspaper for 24 hours so they can purge their guts clean. Otherwise you're going to have a muddy mess in your tank and nutrients to feed an algae bloom.