Niwa fisheries scientist Peter McMillan said the discoveries revealed how little we knew about the ocean's riches - less than 0.002 per cent of the deep sea environment has been sampled.

"The deeper we go, the less we know. Our knowledge of fishes decreases with increasing depth."

Some of the fish he had never seen in 30 years of sampling around New Zealand.

The fish evolve into bizarre body forms to adapt to the intense water pressure, cold water and scarcity of light and food at great depth.

Living in relative darkness, many had small eyes or produced their own light.