I come across people who claim fish is not really a meat. To me, it is an excuse to eat fish, but it also comes from the fact that, in the past, people incorrectly thought fish bred asexually, so eating fish would not trap "souls" in our own bodies. Confusing, I know. Catholics ate fish because they were "abstaining" and also because Jesus was crucified on a Friday so it was a sacrifice to eat fish instead of the traditional meats. Kind of funny to look at this idea now and think of it as any type of sacrifice, but when I saw small, we thought it was a big deal when our Catholic neighbors ate fish. Also, fish was seen as a poor man's food so they saw it as sacrifice to eat it.
In the 1600's the Catholic Church included beaver, some ducks, muskrat and embryos as allowable to eat on Fridays and called them fish! They were in water, after all. (The embryos were in water in the womb.) I am assuming they were some types of animal embryos other than human. I just wonder how they had the nerve to cheat on a sacrificing diet! They believed in God and thought he was watching their every move, yet they conspired to include beaver and any water swimming animal as a fish! Pretty nervy of them! But it shows there was absolutely no moral concern for animals, as the animal would have to have been killed in order to get the embryo out. And it is quite amusing to think that they would eat the embryo, since if allowed to develop, would turn into an animal they would not be able to eat!