I've wanted to draw this idea for... years I think.
This is milotic.
As a nereidae (mostly the nereis genera) inspiered creature.
Here's what wikipedia says about these creatures; [link]

There's many other animals that could fit milotic, but I like invertebrates so of course I choose draw it like a invertebrate. Same with my take on flygon and my hated version of gardevoir; it's all to suit my taste and nothing else.
And I know that feebas is a fish, but I don't care
And I certainly had fun making this XD
(I also would like to draw a barracuda version thought, together with a gyarados. These two pokémon remind me of each other very much, and I draw gyarados as a barracuda faced creature. No sorry, there's no example of this in my gallery.)

Milostic is a large predator that live in the "twilightzone" of the sea, where the light from above barely reaches. It’s intense red colour actually work as a camouflage down there; red appear as black because of the way water filter light.
Prey is rare down there so milotic is rather passive. Most of the time they stand still in the water, waiting for a prey to come by. They'll discover approaching prey with their long antenna that is both sensitive to touch and smell, but also by using their eyes. Once the prey is within reach, the milotic shoot out a special kind of yaws (check thee wikipedia link for details) and snag the prey.
According to DP, the females have bigger ornaments then the males. When an ornament differs between the genders, it generally means that one gender, the females in this case, must be competing over the other for some reason. Maybe the males of milotics care for the young? In any case, I can image that the milotic could go up to the surface at a special time of the year, where they display and compete for partners.

Edit;
The nereis is actually considered beautiful by many; their plates shimmer in a rainbow spectre, like oil. There's even a species named after the goddess Aphrodite, nereis aphrodite. Unfortunate, these beautiful colours don't show well at all in photos, making the worms just look slimy instead of like satin
I think these creatures are called rainbow worms in dutch?

Edit 2;
I ralized that the coulours of the tail is iverted... and that it's too pink <_<
I'll do a manipulation of it later, but it's sad the the original work is stocked with the wrong colours




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