Have you ever seen the web comic, http://www.meekcomic.com/ "The Meek"? Your style and this piece remind me of it.
I have as a matter of fact! thanks for the compliment
you might show her other hand under the belly of the fish. And maybe a coral or something in her hair to suggest more of a mermaid and more femininity? But it's also nice that she's not stereotypically beautiful. :) Whatever.