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Fish are the most varied and diverse backboned creatures on the planet. To date, 28,000 species of fish have been discovered.

From pregnant males to fish that fly and fish that have a top speed faster than a cheetah, the diversity of fish is amazing.

The strange looking weedy sea dragon lives off the coast of south Australia. These brightly-coloured fish appear to have no obvious means of propulsion. In spring, weedy sea dragons gather and the males and females pair up for courtship. Each pair engages in a mirror dance until, finally, under the cover of darkness, they spawn. Bizarrely, the eggs are laid onto the tail of the male and two month later the young weedy sea dragons hatch and, with a shake of his body, he helps them free of their egg cases. His job done, father and offspring go their separate ways.

Other fish's family links last rather longer.

The convict fish is an oddity. No- one knows what the adult eats, as no one has ever seen one leave its burrow to forage. It shares its network of tunnels with thousands of its offspring, which are not bound to the tunnels. They venture out and feed on the rich plankton around the reef – returning every night to join their parent in the safety of their tunnel. They may in some way feed the adult – but how this happens is a mystery.

Even the most enormous natural obstacles don't seem to deter fish.

In Hawaii, famous for its waterfalls, gobies manage to climb them – sometimes over 400 feet – using a specialised disc that enable them to stick to vertical rocks. Their reward at the summit is access to secluded pools and very few predators.

Flying fish are capable of bursting from the water and soaring on 'wings' created by their elongated pectoral fins to escape predators. And their spawning behaviour is astonishing as they mass around any flotsam they find. The action can become so extreme that living fish are entombed in the mass of eggs that the fish lay on floating palm fronds. So many eggs are laid that finally the frond sinks into the depths, bringing an abrupt end to the spawning action.

Fish Out Of Water

Sail fish are cameraman Rick Rosenthal's life passion so he jumped at the opportunity to film them off the coast of Mexico.

They were lucky to hit a bumper year and, with over 30 sail fish in the water at once, the action was extraordinary. For the very first time using a hi-speed camera in an underwater housing, the team were able to film unique footage of these top predators.

Meanwhile, in Tobago another crew led by Doug Anderson were after flying fish.

When flying fish start spawning they do so on a huge scale and anything and everything becomes a target for their eggs – including cameramen and assistants! Eventually the team were forced to abandon the area as the numbers of flying fish were so huge that they risked sinking the boat by laying such a weight of eggs on it.

Undeterred, the crew spent the remainder of the trip filming hi-speed images of the fish doing what they do best – flying – with astonishing results!

Producer: Adam Chapman.