It's ash Wednesday and Fridays that require fasting and white or red meat doesn't have anything to do with it.

It was ment to show piety in giving up more luxurious foods. Fish, grains, milk, eggs, vegetables, fruit all ok, as these were staples that the poor generally lived on.

But because the Catholic church was a bit hypocritical and didn't want to upset the rich too much they decreed that bevers were fish because they swam so were ok to eat when fasting.