Fishes are cold-blooded vertebrate animals that comprise around 34,400 species found in freshwater and saltwater across the globe. Fish fall under the superclass Agnatha (jawless fish) and phylum Chordata which includes hagfishes, sharks, bony fishes and many more. Except for the fish Opah, all other fishes are cold blooded vertebrates. The characteristics of fish are gill slits on the side, skeletal supporting cord and a tail. The study of fishes is known as ichthyology, which has brought light to the importance of fish in the world’s food supply.
Now let’s look at the life cycle of a fish to better understand them.