How to Clean Flounder

Flounder live near the bottom of the ocean. They are flatfish, usually caught in coastal lagoons and estuaries of the Pacific Ocean and the Northern Atlantic Ocean. They typically measure between 5 and 15 inches long (12.5 to 37.5 cm), and their width is usually about half their length. Flounder are popular fish to eat in homes and at restaurants, due to their low levels of fat and calories, and high protein content. Fresh flounder caught in the wild will not have a fishy smell, and their eyes will be bright and clear. Flounder gills have a light red color. Clean flounder thoroughly once it is brought home to prepare it for cooking and eating.


  1. Image titled Clean Flounder Step 1
    Remove the fish slime. Place the flounder on a clean, flat surface. Healthy flounder will be covered with a light film of transparent slime. Rinse the slime off the fish with lightly running cool water.
  2. Image titled Clean Flounder Step 2
    Cut the gills. With a small, sharp knife, cut across the fish, through the skin, behind the gills. The knife should reach the bones of the fish, but not cut through them.
  3. Image titled Clean Flounder Step 3
    Cut down the side of the flounder. Find the flounder backbone, which runs down the middle of the fish from the gills to the tail. Cut along this line, from the center of the gills to the tail. Follow the backbone while cutting.
  4. Image titled Clean Flounder Step 4
    Fillet the flounder. Insert the tip of the knife under the skin, along the backbone. Slice from the gill to the tail, lifting the side of the fish that is coming loose. Keep lifting the fillet as it pulls away from the bone. Continuing cutting until the fillet is separated from the backbone. The flesh should remain attached at the tail.
  5. Image titled Clean Flounder Step 5
    Cut the bottom side of the flounder. Once the top part of the fish has been filleted, make the same incisions under the flesh and next to the backbone, to pull the bottom part of the fish from the bones. Keep the fillets attached to the fish near the tail.
  6. Image titled Clean Flounder Step 6
    Remove the skin. Slide the knife between the skin and the meat of the fish and gently cut the flesh away from the skin. Hold onto the skin instead of the flesh during this process, as the skin is stronger.
  7. Image titled Clean Flounder Step 7
    Flip the fish over. Perform the same steps of cutting and filleting on the other side of the fish.
  8. Image titled Clean Flounder Step 8
    Remove the flounder fillets. Once separated from the bone and the skin, the flounder has been cleaned and is ready for cooking and preparing. Four fillets should be taken from one average flounder.


  • Keep the flounder on ice once it is caught, and refrigerate it immediately after it is cleaned. The fish can spoil if left at room temperature too long.
  • Lay down newspaper before cleaning the flounder. This will make clean-up easier once the process is over. Just fold up the newspaper and throw it away.


  • If the fish slime is white rather than transparent, this indicates the fish may be old. Do not use the flounder if it is covered in white slime.

Things You'll Need

  • Sharp knife
  • Newspaper

Article Info

Categories: Fish and Seafood