Remove the head, collar, and tail and reserve for stock. Using the line down the middle of the fish as your guide, cut with your knife and run down the line and remove the flesh from both sides. While filleting, press your knife down against the bones so you get as much flesh as you can. Repeat with the other side. Flip the fish over and repeat, removing the last 2 sides from the bone. Using a spoon, scrape the bones and reserve this meat for the mousse or quenelles. Chop and reserve the bones for stock. Skin each side, remove any bloodlines and portion into desired sizes.