Here's an experiment I performed, you can try it if you care to. I just went to my preferred search engine and did an image search for "animal".

I had to scroll down about thirty images to find something that wasn't a mammal. It was a lizard. Most of the animals were fuzzy. (I may have missed some marsupials, to be fair.) I believe these search results are reflective of what people are looking for when they search "animal," and it isn't fish.

Are fish animals? I would agree. Is it normal to feel differently? I believe so.

You have to go down pages and pages to even find a hedgehog, and you find very few birds. I think you find very, very few people who wouldn't call an ostrich or a hedgehog an animal, so I don't know how much that experiment says really.