Why do some fish sport beautiful colours? Can they feel pain? What’s special about lanternfish? The piscine world is awash with surprises, reveals a new book

Mind of its own: tightly coordinated fish are schooling, not shoaling Alex Mustard/naturepl.com/plainpicture

WHAT is the most numerous vertebrate on Earth? Not the rat, nor the wildebeest, nor even the domestic chicken. The answer is the lanternfish, a deep-sea denizen rarely seen by human eye, and which number in the trillions.

Eye of the Shoal is a compelling invitation by marine biologist Helen Scales to share her passion for fishwatching. Along the way we learn that guppies are named after Lechmere Guppy, a 19th-century naturalist who worked in the Caribbean, that blueback herring can detect sounds at a frequency …