I start with a photo or photos of the fish, then draw the fish to scale on 100% cotton-rag board. This is the point where the specimen's details are recorded on the board, including spotting and face and fin shapes. I attempt to capture every detail possible from the photo. After the fish is in pencil, I then move on to the coloring, for which I use Prismacolor colored pencils. This type of pencil produces rich, life-like color, and allows me to record fine coloration and subtle variations. The depth in the final art is a product of the color-layering process necessary with colored pencils: colors are applied on top of existing colors on the board, layer upon layer, until complete. I then "burnish" the illustration, essentially going over the entire piece with light colored pencils to eliminate the board's grain. Next, I add the scales using a number of techniques, including etching them in with a sharp knife and applying the scales with a fine brush and acrylic paint.
Thanks Jared, and if you check in here, please comment. I'd love to know how long it takes you to complete an illustration like this one.