Critique of Hippocampus Blue by ~jacij
First off, this is beautiful! It really shows when an artist has studied the anatomy of their subject, and this is a great example of that knowledge. I'll start with the issue you've raised in your comment the soft feel of the horse head. Overall, it does lend the picture a watery look, but you do need to sharpen the more detail-oriented areas of the head eyes, nostrils, inside the ears, and the perimeter of the horse. One of the problems with leaving the horse with such a soft look is the sharp contrast it gives between the horse and the background. I like what you've used for the back, but it is very sharp, so this needs to be equally matched with the foreground (the fish are good in this aspect). Otherwise, your brush strokes are very strong and well placed.
Moving onto the compositional aspect: I like the placement of each foreground object, but I think the middle is too strong. The horse head dominates the piece, not only because it is centered, but because it is so much bigger than the fish. Therefore I get stuck in the middle of the piece, instead of letting my eye wander easily over the entire thing. The fish, with their placement, would easily become the balancing part, so making them bigger would greatly benefit the entire piece. The fish, along with the tail and the fading of the background (on the right), can lend an aesthetically pleasing asymmetry, if used right.
My last comment would be on the colors. I'm not sure if white is the right choice for the overall background, and I think changing this could be used to help make the piece feel underwater. Also, you've used mainly blues throughout the entire foreground clearly, this color is one of the focuses of the piece, but to make it really pop, using another color to help shade or highlight can help. Restraining yourself to just one hue can create a flat look.
All this piece needs is a little tightening up, but it really is a beautiful piece. Keep painting!