Fish dominate the planet's waters through their astonishing variety of shape and behaviour. The beautiful weedy sea dragon looks like a creature from a fairytale, and the male protects their eggs by carrying them on his tail for months. The sarcastic fringehead, meanwhile, appears to turn its head inside out when it fights. Slow-motion cameras show the flying fish gliding through the air like a flock of birds and capture the world's fastest swimmer, the sailfish, plucking sardines from a shoal at 100 mph. And the tiny Hawaiian goby undertakes one of nature's most daunting journeys, climbing a massive waterfall to find safe pools for breeding.