Maybe you're thinking of the Elves in Elder Scrolls who are solely carnivores?
Correct me if I'm wrong, but aren't just Bosmer strictly carnivorous, and only for cultural/religious reasons? I don't think I've heard about all mer being carnivores (though perhaps I'm poorly informed).
I'm hardly an expert on Elder Scrolls lore but yes, it's the Wood Elves" in the Emerald Forest who strictly eat meat, I don;t know if it's because they can't metabolize anything else or if it's a "super-environmentalist" cultural/religious thing, I think both are cool.
