The carving pictured is a grayling that I did in a class with Ed Walicki. Ed is one of the premier fish carvers in the world and I was blessed to be able to spend a week with him in his studio. I learned more in five days than I would have learned in five years on my own.
Everything you see is wood except for the fin that holds the fish to the environment. That fin is carved out of aluminum. Every scale was burned in by hand one at a time.
I really do love carving fish but it's such a commitment that I don't do it very often anymore. I'm not setup to do it right now anyway as I don't have a good place to setup my dust collector at our new house.
If you are interested in fish carving I definitely recommend you find someone to take some classes from. You can undertake it on your own but it can be overwhelming. While the fish I have carved won't win any world championships I can definitely tell a difference between mine and those who have not had any instruction. The most telling is usually the fins. A natural looking fin sets off the whole carving.