What is a fish? Many people may be surprised to find that this is a difficult question to answer. This volume investigates the incredible diversity of the aquatic lifeforms we call fish, from colorful coral reef dwellers to the deep-sea giants that lurk in the ocean's darkest depths. Through the age-appropriate main text, enhanced with vivid full-color photographs and in-depth sidebars, readers learn about the habitats, characteristics, and environmental role of various fish species, inspiring students to protect the oceans and their incredible inhabitants.