Fish are vertebrate animals that live in water. They have skeletons, breathe through gills, and have fins and scales. There are three main types of fish: jawless fish like lampreys, cartilaginous fish like sharks that have skeletons made of cartilage, and bony fish which make up most fish and have skeletons made of bone. The document then focuses on bony fish, describing carp specifically - they have scales, lay many eggs, and are omnivores that eat plants and small animals.