Some types of fish are sharks, rays, lampreys, catfish, lungfish, herring, tuna, pufferfish, coelecanth and gobies. Other types include angelfish, tetras, gouramis, cichlids, guppies and goldfish. Each of these refer to general types of fish, and each type may include many distinct species or varieties.
There are over 27,000 different recognized species of fish in the world, which makes them the most diverse vertebrates on the planet. For example, the Chondrichthyes include sharks and rays; the entire class is made up of about 800 distinct species, including tiger sharks, nurse sharks, thresher sharks, great white sharks and hammerhead sharks. The largest species of fish in the world, the whale shark, also belongs to this class. This class of fish is distinct for having cartilaginous skeletons.
The vast majority of fish species belong to the Osteichthyes, which comprises 95 percent of all fish species. Fish species in this class are also known as bony fish, referring to their skeletons, which are made of bone as opposed to cartilage. The most abundant species of fish in the world is the Atlantic herring.
Fish such as angelfish, tetras, cichlids, guppies and goldfish, all freshwater fish, are common aquarium pets known for their bright colors.