Fishes (singular: Fish) are a paraphyletic group of aquatic vertebrates, with approximately 25,000 species. It should be noted that there isn't a single specific class for fish. There are actually three: jawless, bony, and cartilaginous fish. Fishes are characterised by a lack of limbs and the presence of fins and scales (in most cases) in their place.
Fishes have a variety of feeding habits, with the groups following all three of the three main feeding behaviours of carnivory, herbivory and omnivory. A large number swallow food whole or shake it around to break it into smaller chunks; sharks and rays are the main exception, as they have sharp teeth capable of tearing flesh.