New Zealand scientists say they have found fish species previously unknown to science after trawling almost 3 kilometers beneath the waves in the southwest Pacific.

Scientists from the National Institute of Water and Atmospheric Research (NIWA) made the discoveries when they conducted their deepest-ever trawl at 2,730 meters deep near the Chatham Rise, an underwater plateau that runs for about 1,000 km off the east of New Zealand.

The trawls revealed "truly fantastic looking new-to-science and rare fishes," including a flabby whalefish, three new slickheads, a juvenile Richardson's skate, large warty cusk-eel, and several unidentified fishes, said statement from NIWA.

NIWA fisheries scientist Peter McMillan said in the statement it could take at least three hours to send a net to the sea floor at 2,000 meters and get it back.

Deep sea fish often appeared to have "bizarre" body forms compared with the more commonly studied inshore fishes.

NIWA had given the rare and the new-to-science fish to New Zealand's national museum, Te Papa in Wellington, where they were preserved, researched and stored in the National Fish Collection.

The trawl was part of a study of fish stocks and distribution in New Zealand's exclusive economic zone, the waters extending from 12 nautical miles to 200 nautical miles offshore.

"We are interested in these results because they test whether our assumptions about the depth limits of commercial fish species are correct, and they also increase our knowledge about the inhabitants of our marine estate in this largely unexplored environment," Dr Pamela Mace, of the Ministry for Primary Industries, said in the statement.