Once a boy who loved the sea and now a marine biologist, Doctor Jung-gu Myung vividly tells about the lively fishes and seas all around the world.

The seas--the place where the species harboring the secrets of proto-Earth live and where the feast of various life phenomena such as the evolution, extinction, and birth of new species is held. The seas of the polar regions, temperate climate regions, and tropical regions are full of diverse marine life, and there the uncharted waters wait for humans to research.

Professor Jung-gu Myung, a recognized fish expert, has traveled seas all around the world encountering diverse species of fish with underwater investigations and has studied the underwater world. The author, who has dedicated his entire life to studying fish, marine ecosystem, and fishery resources, has gathered the stories of his own into a book as he wraps up his research career. He vividly tells stories about the ecology of fish that he has discovered through aquanautics and delivers his philosophy about the sea and life as well as the process of his growing from a marine boy who dreamed about the sea into a marine biologist.

Do fish have good eyesight? Which senses do they have? Is it true that there is a fish that can change their sex? What is the biggest fish? What is the smallest fish in the world? In the first chapter, the fish expert provides mysterious and amazing ecological knowledge about fish. He covers the basic information such as shapes, sizes, sensing organs, breeding strategies, parasitism, symbiosis, and handling of fish with much expertise. The author claims that the senior member of the Earth is fish. What should human beings that live on the land learn from fish? Humans have been destroying not only the land environment but also the marine ecosystem by encroaching upon it. However, marine life including fish have been keeping the order of the ecosystem for billions of years. In the underwater world there live predators such as sharks and whales and small fishes like anchovies, sardines, and mackerels, forming an ecological balance. The author shows how humans break the food chain under the sea by capturing millions of sharks in order to cook Shark Fin soup and overfishing other marine species and insists that humans learn from fish, how to live a harmonious and moderate life.