How deep can a fish go? Scientists say strange fish caught near New Zealand may provide answer

WELLINGTON, New Zealand – They might look like offal stuffed in cellophane, but five fish hauled up from near-record depths off the coast of New Zealand are providing scientists with new insights into how deep fish can survive.

In a paper published this week in the Proceedings of the National Academy of Sciences, scientists from the U.S., Britain and New Zealand describe catching translucent hadal snailfish at a depth of 7 kilometres (4.3 miles).

By measuring levels of a compound in the fish that helps offset the effects of pressure, the scientists say they’ve concluded that fish likely can’t survive below about 8,200 metres (5.1 miles). That would mean no fish live in the deepest one-quarter of the world’s oceans.

The snailfish have little pigmentation due to the lack of light in their environment.