What Are the Different Types of Fish Species?
Fish species are a very diverse of set of aquatic animals adapted to living underwater. The main characteristics shared by most fish species are that they live in water, breathe with gills, have scales, and swim with their fins. A species is the most specific biological category and refers to a group of similar animals that can breed with each other, but not with other species. Fish species have adapted to many types of aquatic habitats and therefore can be very different from one another. One basic distinction can be made between freshwater and saltwater fish. Fish are classified as vertebrates, meaning they have a backbone or spinal column. Vertebrates include land animals like birds, mammals, reptiles and amphibians. Fish are in fact so diverse that there are more individual fish species than all of the other vertebrates combined. The total number of fish species has been estimated to be about 20,000 or more.
