The process:
I started out with a very loose pencil sketch and started inking on hot press watercolor paper.
Here I finished inking and then waited for the ink to dry before erasing the pencil and taping it up to be painted.
I watercolored the sea first because it was easier to get those random gradations of color without worrying about precision.
The process with the fish was a bit more precise. Then I brought it into photoshop to make the colors a bit more saturated and give it more of a "deep sea" effect. You can only get so dark with watercolor.
Some details:
