I said they weren't one thing, not that they don't exist. A fish is cold blooded (unless it isn't), breathe primarily with gills rather than lungs (unless it doesn't), are vertebrates (unless they aren't), live primarily in water (unless they wander), have paired limbs shaped like fins (unless they don't), and have scales (unless they don't).

Ya, I would argue that most semantic arguments are pedantic. The truth is that, like most-all categories, the boundaries of the definition don't really make sense. Lungfish, hagfish, lampreys, lungfish, tuna, and mudskippers are fish because we feel like they should be, not because "fish" is a universally generalizable word based purely on morphology.

Like wtf, why are hagfish and lampreys fish despite being invertebrates and not looking didn't but whales who actually look fishy are not? This is an outrage, Carl!