Anchovies: Anchovies are small saltwater fish of the herring family. Rarely eaten fresh, they are usually sold in cans or jars and are used as a seasoning. Anchovies are a classic ingredient in salade Niçoise and Caesar salad, and are also a popular pizza topping. The tiny fillets are heavily salted and packed in oil.
http://www.berkeleywellness.com/healthy-eating/food/article/types-fish
1 Some fish have a dark tissue lining the abdominal cavity that can be scraped off to prevent a strong, oily flavor. 2  Remove the head if you like, trout are often cooked with the head on.  Clean your fish-cleaning table immediately, collect the guts, heads, and scales, and discard them properly.
https://www.takemefishing.org/how-to-fish/how-to-catch-fish/how-to-clean-a-fish/
If you are planning on cooking your fish whole or if you are going to steak it, rather than filleting it, cleaning your fish is a must. To begin, rest the fish on the table or cutting board. Insert the knife tip into the fish's belly near the anal opening and move the blade up along the belly, cutting to the head.
https://www.takemefishing.org/how-to-fish/how-to-catch-fish/how-to-clean-a-fish/
Mullet: Most of our saltwater mullet comes from Florida, with silver and striped mullet the most common species. This fish has distinctive areas of dark and light meat. The dark meat is strong-flavored and oily, while the light flesh is mild and sweet. Buy mullet dressed for baking, broiling, grilling, or sautéing.
http://www.berkeleywellness.com/healthy-eating/food/article/types-fish
Now that you have a clean fish, or prepared your steaks or fillets, you can store your fish or cook your fish! Check out our favorite cooking methods and recipes as well. Fish fins can be very sharp and cause serious puncture wounds, so be very careful when learning how to fillet a fish or clean a fish whole.
https://www.takemefishing.org/how-to-fish/how-to-catch-fish/how-to-clean-a-fish/
1 Some fish have a kidney by the backbone. Remove it by scraping it out with a spoon or your thumbnail.  Rinse the cavity out with a good stream of water and wash the skin. Some fish have a dark tissue lining the abdominal cavity that can be scraped off to prevent a strong, oily flavor.
https://www.takemefishing.org/how-to-fish/how-to-catch-fish/how-to-clean-a-fish/
This Is Why You Want to Take the Dark Meat Out of Your Fish. by Owen James Burke. This is the secret to not only making fish taste better, but avoiding poisoning. I’ve always pulled the dark red meat (brown, once cooked) out of fish before cooking it, if not after.
http://thescuttlefish.com/2015/01/this-is-why-you-want-to-take-the-dark-meat-out-of-your-fish/
1 Some are packed whole, while others are skinned, boned, and sold as fillets.  Shad: This member of the herring family is famous for its tasty roe as well as its rich flesh. Shad is one of the fattiest of all fish. Like salmon, shad is a fish that lives most of its life in salt water, but spawns in fresh water.
http://www.berkeleywellness.com/healthy-eating/food/article/types-fish
If you are planning on cooking your fish whole or if you are going to steak it, rather than filleting it, cleaning your fish is a must. 1  To begin, rest the fish on the table or cutting board.  Keep the knife blade shallow so you don't puncture the intestines.
https://www.takemefishing.org/how-to-fish/how-to-catch-fish/how-to-clean-a-fish/
This Is Why You Want to Take the Dark Meat Out of Your Fish. This is the secret to not only making fish taste better, but avoiding poisoning. Photo via Commuter Cruiser. I’ve always pulled the dark red meat (brown, once cooked) out of fish before cooking it, if not after. It’s what some people call the blood line, the set of nerves that make up a fish’s lateral lines, and it’s often what gives fish that undesired fishy or earthy taste.
http://thescuttlefish.com/2015/01/this-is-why-you-want-to-take-the-dark-meat-out-of-your-fish/
what is the dark area on a fillet of fish?
 The dark area on a fillet of fish is a dark tissue lining the abdominal cavity. The dark area on a fillet of fish is a dark tissue lining the abdominal cavity.