I really like your idea! It fits with her champion without being 'obvious', and it's great that you thought about the culture around the Mandarin fish to inform the rest of the design. Personally I find it a bit hard to focus on her face which I think is because it doesn't have much contrast with her neck/fins. If there was a bit more variation in terms of light and shadow near her face it would bring it out more - however you may not want her face to be the focal point, which is fine! Just something to bear in mind :) Also, the headpiece she's wearing blends in to her head-fins because they're pretty similar colours.
The bright colours in general really work for me - if you want to add depth play more with pumping up your shadows and having a clear direction that the light's coming from. Other than that, I think it's awesome. I love the pose you've done, it looks very dynamic and has good flow. I hope my critique is helpful!