You're waaay better than me so I shouldn't be making any critiques especially as this is such an amazing picture, but maybe after the buttock-thigh area you could blend the tail a bit more so it looks less like two legs fused together (you can tell where the original legs were) and more like a single solid mass. Other than that I think this is absolutely brilliant!!! I totally LOVE the coral and the wisps at the end of her tail, so ethereal and beautiful :D