This is truly a mermaid hair!
I saw this on a feed and immediately thought the hair resembles a fish! I mean the shape and everything looks legit. The braids are like the scales and the fishtails really does remind me of a fish tail. I was trying to find the tutorial for this exact hairstyle but no luck. I did find a tutorial that is close enough to this one by the same hairstylist.
The only difference is the method of braiding on the top. Notice the at the previous photo it's a dutch braid at the crown. For this one, fishtail braiding is done. Anyways, either braiding style works! Just pancake the braids out so it looks chunky!