There's something about fish that leaves a cold, slimy whiff in many people's minds. Either that, or fish are simply `food'; catching fish to eat is so deeply ingrained that we fish for fish, but we don't pigeon a pigeon or deer a deer. It's difficult to think of fish as wild, living things, partly because those chunks of white meat on our plates are almost impossible to connect to animate, living, breathing creatures, in the same way a steak doesn't call to mind a mooing, cud-chewing cow. To make matters worse, fish inhabit a realm beyond our normal, everyday experiences. Wild fish hover in seas, rivers and lakes, out of sight and out of mind. But from the very first time Helen Scales immersed herself into their liquid world, she realised that fish are beautiful, mesmerising, complex and exciting. The moment she sank down to eyeball a wild trout - the fish poised in front of her, expertly occupying the three-dimensional space in a way that she could only dream of imitating - sparked the ichthyologist within, and set in motion years of study and exploration in the fishes' unseen domain as she became a devoted fish-watcher. In this book, Scales shares the secrets of fish, unhitching them from their reputation as cold-hearted, unknowable beasts and reinventing them as clever, emotional, singing, thoughtful animals, and challenging readers to rethink these animals. She takes readers on an underwater journey to watch these creatures going about the hidden but glorious business of being a fish. Their way of life is radically different from our own, in part because they inhabit a buoyant, sticky fluid in which light, heat, gases and sound behave in odd ways. They've evolved many tactics to overcome these challenges, to become megastars of the life sub-aquatic, and there are many different ways to be a fish; these extraordinary, diverse animals tell us so much about life, the oceans and everything. Woven throughout will be stories of how fish have splashed into our world, and not simply as food. Our relationship with these scaly creatures goes much deeper than predator versus prey. Fish leave their mark on the human world. As well as being a rich and entertaining read, this book will inspire readers to think again about these animals, and the seas, and to go out and appreciate the wildness and wonders of fish, whether through the glass walls of an aquarium or, better still, by gazing into the fishes' wild world and swimming through it.