Rules for easting (and not eating) in Lent
First, let's look at what the rules are:
• All Catholics who have reached their fourteenth year are bound to abstain entirely from meat/poultry on
-- Ash Wednesday and
-- all the Fridays of Lent.
• All Catholics between the ages of eighteen and fifty-nine inclusive are also bound to observe the law of fast on Ash Wednesday and Good Friday.
This means limiting oneself to a single full meal and avoiding food between meals. Two other light meals, which together do not equal a full meal, may be taken during the day.
• Those whose work or health would be impaired are excused from fast and abstinence. Individual conscience should decide proper cause for excuse. A more serious reason is required to excuse oneself from Ash Wednesday and Good Friday fast and abstinence.
And yes, chicken is considered meat.
And none of the regulations mention fish. There is no rule that people should eat fish in Lent.
So why NOT abstain from fish? Why meat?

Before we get to the meat and fish thing, first a little background.
There were no Stop n' Shops in the middle ages. No electricity, no refrigeration - except for the ice and snow of the winter months. It makes you wonder how people had enough food to live on. Forget fresh fruits and vegetables. There would have been root vegetables (potatoes, carrots, beets) and grains, and cabbage keeps pretty well all winter.
To preserve food, they would have used salt, smoke and pickling. And if you had enough hay to feed livestock, you could keep them through the winter and butcher them when needed. Most families had live chickens as a source for eggs and meat. But once the food was eaten (or spoiled, or eaten by mice, rats, or other vermin) there was no more food.
No more food. No ShopRite. No Trader Joe's. So what did people do? They died. Starved to death. Or, in a malnourished condition, they succumbed to disease.
What saved whole communities was the Lenten practice of fasting. If I “gave up” eating as much food as I'd like, if I abstained from killing an animal for meat, I would be able to stretch out the food supply for another month 'til spring arrived and there'd be new crops, new lambs, etc. And if, by cutting back on what I ate, I could share the little I had with others in my family and neighborhood, they could survive the winter too.
Fasting requires a choice to be unselfish, to deny something in myself in order to do good for others. And in a society where death came quickly to so many, the temptation would be to look out only for one's self. It was survival of the fittest. But when parishes started introducing Lent as a time of fasting, they were giving spiritual encouragement to people to be less selfish - and the by-product of “giving up” in Lent was that lives were saved. Indeed whole neighborhoods were saved from starving to death because they all made a faith-commitment to fast and to share.
Today fasting is not as essential to the survival of our families. It's actually a luxury because it's a choice we have. Too much of the world (including those who live in America - indeed some who live in our neighborhood) doesn't have the luxury of “giving” up food. They just go hungry many days of the year.
But for many of us Fasting has become a way in which we can say to God, “Look at how good I can be for forty days! See, I'm really loveable.” Fasting becomes like a proof of our self-control. And when we succeed in giving up the smoking or the calories or the swears, we beam inwardly and imagine God smiling on us a little more broadly this year. When we fail, we kick ourselves for our failures, and throw this year's broken resolution on the heap of our past failures. So we need to be reminded this Lent: God doesn't love us any more or less if we succeed or fail at fasting. God loves us with an unconditional love. God smiles at our very existence and on the days that we fall down God, like any loving parent watching a child fall when trying to walk, speaks one word to us…..”UP!”
“Ashes, ashes we all fall down,” so goes the song. And every time we fall down, God says “UP!” - and reaches out a hand and pulls us to our feet to try again. So let's get over this idea of our being failures when we break our fastings. Let's get up and get on with fasting. It's meant to be an unselfish choice that is life giving. So whether we're fasting from fear or from food, from sarcasm or sweets, let's rediscover the life-giving reasons our parishes engage in fasting in the first place.
So what about meat and fish?

There are two theories as to why meat was chosen to be the food to be given up on Ash Wednesday and the Fridays of Lent.
The survival theory. This matches what we wrote above. If you eat the last lab of the flock, you have no flock in the spring.
Abstaining from meat means your animals live long enough to produce offspring.
Fish, on the other hand, were a plentiful source of protein -- even when lakes froze over you could go ice fishing. There was no concern about over-fishing. No need to abstain from fish. And because fish became the favored protein source during the Lent time of the year, it almost became the prescribed protein.
But we can get our protein from other sources (e.g. eggs, beans, nuts, etc.) and one goal to abstaining from meat is to live more simply and choosing food that has the least detrimental effect on our only planet. Lobster? Not a Lenten food.
There is only meat theory. This certainly was not the experience of most people struggling to survive. But there was an upper class that lived on all sorts of meats -- deer, wild boar, roasts of game birds, etc. Think "Henry the VIII" here with a royal table groaning with meats of all kinds at all meats. So if the church asks the upper class to abstain from meat, they are really being asked to do a big fast.
So in summary, we don't eat meat on Ash Wednesday and the Fridays of Lent.
We fast on Ash Wednesday and Good Friday.
This is not complicated.
And chicken is meat.
