Okay so Atquati needs more of a fish right?
So why not have a dolphin-horse? Kind of like the Hippocampus.
It would have a dolphin-like tail to replace its back legs and tail, Spiny fins on its back, it would only have two front legs that have webbed hooves, gills, maybe its eyes could look somewhat like a seahorse's, and perhaps the ears could be shaped like giraffe horns than horse ears. I'm not sure what else.
Baby: It would have the beginnings of sharp fins in different places on its body. It would have the face of a foal, the giraffe horn-shaped ears on its head would start as just small lumps so it couldn't hear at first, a dolphin tail to replace the back legs and tail, it would breath through gills, and have webbed hooves.
Middle: The spines would be almost fully grown, full hearing ears, the tail would be pretty much the same, gills as well, and the webbed hooves are no different either.
Adult: Probably not much different from the teen, just much bigger with larger spines and a more matured face than when it was a foal.
I didn't draw this but it works good to explain what I'm talking about.
Here's a picture of a Hippocampus:
The only differences from the picture would be:
- Gills
- Webbed hooves
- Giraffe horn shaped ears
- Seahorse eyes