![School of Fish](https://thepetwiki.com/wp-content/uploads/400px-School_of_Fish.jpg)
Water covers over three-quarters of the earth’s surface and fish are the most numerous of the vertebrates. There are about 31,500 species of fish and they are classified by physical characteristics, habitat, behavior etc.
List of fish families:
Water covers over three-quarters of the earth’s surface and fish are the most numerous of the vertebrates. There are about 31,500 species of fish and they are classified by physical characteristics, habitat, behavior etc.
List of fish families: