Originally posted by DelSolGirl
Color me confused... where did you get the idea that eating fish on Fridays is a sin? 
Catholics (and possibly other denominations, although I can't say for sure, as I was raised Catholic) are supposed to eat only fish on Fridays during Lent (the 40 days before Easter). No red meat is allowed.
The funny thing about this "rule" is many Catholics think it's in the Bible somewhere, that they're only supposed to eat fish on Fridays, like God commissioned it. 
Turns out it was established long ago by the fishing industry -- they weren't making enough money, so they turned to the Church for help.. and thus, fish on Fridays was born.
not much of a surprise there... a lot of the "sins" have a shady background