Stray voltage is common in reef tanks with all the equipments that are submerged in water, make sure your equipment are grounded for your own safety. If the shock you felt was mild I don't think this is the reason why fish stop eating, I believe its mild because you only felt it through a cut, which is usually sensitive to anything. My advice is to monitor the fish for other symptoms that may caused them to stop eating.
Are you dosing any medications in tank? Anything newly added?