It very beautiful. I love the concept The koi is very colorful and bright, and this whole picture is very inviting. But, this is the hard part. Although the piece looks better than what I could do, Korra looks manly. A very attractive manly, mind you. The jaw line looks very angled and the sweatpants contribute to her having an even broader stature. Perhaps you could soften her jawline and chin? Maybe if we could see some more folds on the sweatpants, it could give her bottom half a slimming effect. But what am I blabbering on about, I'm still impressed
Stunning. I love the darker, sketch-like lines you kept for her upper half, particularly the fur. The sleeves are gorgeous, and the fish could easily be a separate (and equally stunning) deviation.
Also, it's delightful that the bottom half is soft, like a watercolor painting. The number of styles incorporated into this piece make it feel almost like a quilt, with distinct "patches" working together to make a rich and lovely whole.
I didn't recognize her as Korra from the thumbnail, but that is not a criticism in my mind. It has power and beauty without being explicitly a fanart.