Eels are fish

While reading an article, I went to check how an eel differs from a lamprey - and I found out that a lamprey isn’t actually a fish

"Lampreys /ˈlæmpreɪz/ (sometimes inaccurately called lamprey eels) are a group of jawless fish"

I'm not sure what you mean? Jawless fish are pretty far from most fish but that's not much of a reason to say they're not fish.

GPT-5 says that now its not. So while lampreys are technically fish under traditional definitions, modern evolutionary science places them as one of the most primitive branches of vertebrates—not part of the “true” jawed fish group.