It is literally impossible for us with our human eyes to perceive these fish in anything like their natural environment.

They aren't even black, to us. We evolved to see things in sunlight. These fish are black at the wavelengths present in the deep. That isn't sunlight but luminescence. Shine sunlight on them and they could be any colour, something irrelevant for a fish that may well live without ever seeing sunlight. So we have a black fish illuminated by a light our eyes were not designed to see, in a place so dark we see can see nothing. Those aren't great preconditions for an accurate photoshoot.