Here's a pedantic remark to make my first contribution on this website: These appear to be arthropods, rather than fish. The first appears to depict a lobster or crayfish, the second and third pictures appear to depict horseshoe crabs, and the fourth picture is unrecognizable to my eye. Fish are considered to constitute all vertebrates minus the tetrapods, whereas arthropods are invertebrates, and a type of protostome.