Okay, so Ponyo isn't exactly a full-blown mermaid, but "nitrosilver98" of pixiv told me she'd be perfect for this year's DeviantArt "Mermay Challenge". Ponyo and her sisters are the offspring of an intimate relationship between an ordinary human and the Queen of the Sea. The only thing different about Ponyo is that she's the only one to take on human form and spend time on dry land. At least that's what he told me about the movie since I never saw it.
Hope you like this anyway.

The background for this fanart was made by chefcheiro of Inkbunny http://www.inkbunny.net/s/2588808
The drawings were made by me.
The character was made by Hiyao Miyazaki for Studio Ghibli.