"I think that this is why fish has always been given a pass -- it is not a stored food that would go bad."
Fish and meat both were preserved by salt curing in the middle ages.
I'm reading a history of salt right now that discusses this sort of thing.
In Medieval Europe, meat wasn't just forbidden during lent, it was forbidden during MANY "holy days," by the late middle ages as much as half the year was meat free.
Civil punishments for eating meat on a holy day could also be quite severe.
In Christianity the origins of not eating meat during certain periods apparently arose in the Catechisms as early as a.d. 98 and was an extension of pagan traditions as were many activities in the early church.
