I have a clown knife fish and I am considering feeding live feeder fish is it cruel???

I have seen many people moan about feeding live fish yet they quite happily munch down on a bacon or chicken sandwich etc without consideration for thow that creature was prepared. IS it a case of if it comes on a packet then we don't have to think abotu it so it's ok ?? I aks as I live in the UK and it is considered wrong to feed live fish. I however eat fsh, Cow, Pig etc and is that wrong too??