The species that live on the surface have, as a general rule, a blue back and silver belly.

In this way it is possible for them to escape the sight of their enemies; seen from the shadows of the depths, they are confounded with the white and luminous color of the surface.

The sardines that swim in shoals are able to pass unnoticed, thanks to their backs blue as the water, thus escaping the fish and the birds which are hunting them.
Living in the abysses where the light never penetrates, the pelagic animals are not obliged to be transparent or blue like the neritic beings on the surface.

Some are opaque and colorless, others, bronzed and black; most of them are clad in somber hues, whose splendor is the despair of the artist's brush, incapable of imitating them.

A magnificent red seems to be the base of this color scheme, fading gradually to pale pink, violet, amber, even losing itself in the milky iris of the pearls and in the opalescence of the mother-of-pearl of the mollusks.