Ok so the most amazing reblog I've seen of this says:
There's a globe-spanning layer of mesopelagic fish that is so dense it distorts SONAR. For decades we had no idea what created the Deep Scattering Layer or why it moved. We still know almost nothing about it.
It contains 65% of all fish biomass.
Marine Ecology has Dark Fish.
And:
FYSA: 65% is a low-end estimate. Dark Fish may comprise 95% of all fish biomass, but we just don't know: https://phys.org/news/2014-03-ninety-five-cent-world-fish-mesopelagic.html
