If you really want to get into traditionally, meat used to also refer to vegetables, a.k.a. green meat. The word meat comes from the Old English word mete, which referred to food in general. More recently, green meat might have referred to animals fed exclusively on vegetables or plant based feed. And today, with the existence of veg-burgers or Beyond and Impossible meats, those are also sometimes called green meat.
So take me back a few centuries, and everything you eat would be mete, including that fish.
The cow is sacred in India, so they don’t eat beef. Most of the Western world won’t eat dog or cat, but that isn’t a universal thing and while probably not as common today, it doesn’t mean that it’s an unheard of practice. Until recent times, people would eat what was available which didn’t have alternative value.