Well 55% of all light hitting the ocean etc, is gone at 1 metre of depth and all light goes into the ocean via a visual
circle called Snells Window, which is seen by all things in the water looking up. That sets the fishes view outside the
surface but if the wind is up, the sea is up etc the light out is minimized.
Pelagics dont see red. And ALL red is gone at 10 metres.
But fish see things that are illuminated by light from the surface, and reflected, but not everything is reflected. Some is absorbed. And if that reflective body is a fish, its camoflaged and that makes it hard to see, for other fishes and us.
These days, when I can use flies, they are chartruse and either straight chartruse or fluorescent. All else is redundant.
Fish are different from us, mostly they do not have variable pupils, or eye lids which tends to force them down a bit in depth. Like the only way they can attenuate light from the surface is look down or go down. And when they are hunting like chasing fish in schools, they use binocular vision.
Fish are food, for other fishes, and they did not appear yesterday, they have evolved to live in the ocean, and to be very hard to see under ALL light conditions.
Like schools of small fish get in a closeup heap, to make a big black blob, which tends too put binocular vision fishes
a bit off. They generally try to bust the blob up, which then tries to get under boats, or other blobs.
And a live prawn might emit all sorts of colours but a dead prawn is dead, and there are few dead prawns in the ocean
emitting anything.
Cheers. Max