Yo Kiki~!
As a fan of the dark and monstrous (and also a lover of "unconventional" mermaids) I'd def be up to help you with your project =v=)/)
I can help on the Sprite work & CGs but not the UI.
✨ And here is my Commission Info ✨
Since this is possibly a more long term project I am willing to discuss & work within your budget so just let a demon know 
You can reach out to me via my Twitter, however we can primarily work with Discord if you'd prefer.
If you have any questions feel free to ask away and I'll try to answer as best I can!
I wish you the best and hope to hear from you soon✨