OceanDeep Sea
Below 8,400 metres, there are no fish. There can't be.
No fish appears able to live below about 8,400 metres. The deepest ever filmed was a snailfish at roughly 8,300 metres, and biologists think the limit is chemical: the molecule fish use to keep their proteins working under pressure maxes out, leaving the ocean's last 2,500 metres to invertebrates.
Step by step
- The deepest fish ever filmed was a snailfish drifting at about 8,300 metres.
- Below roughly 8,400 metres, fish biochemistry appears to simply fail.
- The pressure-protecting molecule in their cells maxes out; the final stretch belongs to invertebrates.
Source
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