Introduction: How to Clean a Fish
People all around the world eat fish and, since one-third of the world’s population lives within100 km of a coastal area (NASA), it is a readily available source of food for a significant part of the world’s population. In fact, the Food and Agricultural Organization for the United Nations reported that in 2016, the Global per capita fish consumption had risen to above 20 kilograms a year (FAO), the highest it has ever been. Not only is fish a very popular food, it is also nutritious as it is a good source of protein and omega-3 fatty acids (EDF Seafood Selector).
While ready to cook fish is made readily available in most supermarkets, one may also need or desire to prepare a meal involving fish that has been freshly caught or bought as a whole fish from the supermarket. As such, a necessary first step for preparing a meal with fresh or whole fish is to “clean” or gut the fish. Below are the steps for how to clean a fish without large scales. If your fish has large scales, you will need to remove them first. For best results, read the instructions all the way through before beginning.
In this Instructable, you will be handling a sharp object and a potential source of pathogens. Use proper knife handling skills. Also, through the course of cleaning the fish, you will see blood and fish guts (viscera). If you become light headed at the sight of blood, you should reconsider performing this activity and take extra precautions if you choose to proceed.
Step 1: Thaw the Fish
If fish is freshly caught and/or not frozen, proceed to step 2. These steps are the first steps because thawing a fish will take time.
1-A. Overnight Refrigerator Thawing
If the fish is frozen, thaw the fish by covering it and placing it in the refrigerator overnight.
1-B. Quick Thaw
If you wish to thaw the fish more rapidly (30-45 minutes, place the fish in a bowl of cold water until it is thawed. Fish will be free of frost and pliable when thawed. Following the food safety guidelines found FDA’s website that appears below might help prevent foodborne illnesses that might occur as a result of thawing the fish. https://www.fda.gov/food/resourcesforyou/consumer...
Step 2: Familiarize Yourself With the Basics in Fish Anatomy
To best understand the steps that follow, it is helpful to have a very basic understanding of fish anatomy and the directional terms used to describe fish anatomy. To do so, study Figures 2a and 2b. The terms that appear below will be used throughout the rest of the instructions and will serve as landmarks for some important cuts that must be made.
Step 3: Familiarize Yourself With the Basic Directional Terms of Fish Anatomy
Use the figure 3 to understand the directional terms associated with fish anatomy and use them for reference as needed. They will aid in knowing in what directions cuts should be made in the future
Step 4: Gather Supplies
4-A. General Information.
Cleaning a fish can get messy, especially if you are inexperienced. However, if you gather the necessary supplies before you begin, it is more likely that your cleanup will be kept to a minimum. The materials you will need to clean the fish are:
2. A sharp, non-serrated knife.
3. A place to dispose of the fish viscera
4. A cutting board to further filet and/or remove fish scales as needed
(See Figure 4a).
4-B. Water Source
It is useful to have a readily available water source while cleaning a fish. If you are cleaning the fish in the kitchen, you can use either running water from the faucet or a large water-filled bowl as your water source while cleaning your fish. If you are cleaning your fish in the pond or river where you caught it, you can use the water from said body of water to aid in the cleaning of the fish.
If you are cleaning the fish in a kitchen sink, make sure sink is clear of any other objects. Also, make sure the sink has a drain filter or disposal so that pipes do not get clogged with the fish viscera.
4-C. What Knife to Use
While commercial filet knives are sold, any sharp, non-serrated knife that is not too large to be easily maneuvered can be used. Remember, a sharp knife is safer than a dull knife (Figure 4b).
4-D. Cutting board
For safety reasons, use a plastic cutting board. Wood cutting boards can be used, but they are more susceptible to the transmission of foodborne illnesses.
4-E. Fish Viscera Disposal Supplies
Fish viscera can be disposed of down the drain (if you have a disposal in your kitchen sink and if you don’t mind the possibility of your sink smelling like fish for a little while after you clean the fish), in a plastic bag to be thrown away in the garbage later on, or in the water where you are cleaning the fish if you are cleaning the fish where they were caught.
Step 5: Stunning the Fish
If the fish is already dead, proceed to step 5. If the fish is still alive perform this step before proceeding. Apply a firm blow to the dorsal surface of the fish’s head with a blunt object. This is done for two reasons. The first is to knockout/kill the fish so that it will not experience any pain during the cleaning process. The second reason is so that the fish does not move while you are cleaning the fish for safety reasons and so that you do not lose your fish if you are cleaning it in the body of water from which it was caught.
Step 6: Holding the Fish
Once the fish is stunned (if it needed to be stunned), it will be easier to hold. Hold the fish in your non-dominant hand so that the fish’s ventral surface is facing upward. Your dominant hand should be used to hold the knife (Figure 5). It is important to hold the fish firmly enough so that it does not slip out of your hands. However, do not squeeze the fish too tightly because the fish’s meat can be damaged if you do this. Since wet fish are sometimes slippery, it might be helpful to pat the fish dry with a paper towel before handling the fish.
Step 7: Locate the Fish’s Anus and Urogenital Opening (Vent)
Fish have a common opening for their urogenital and digestive systems called the vent. Using the figures found below and in step 2, locate the fish’s vent. The vent of most fish species can be found along the midline of the fish’s ventral surface, just anterior to the anal fin (See Figures 2a, 2b, and 7.)
Step 8: Cutting Out the Fish's Vent
Make a “V” shaped incision on the anterior and posterior margins of the vent. To do so, hold the fish in your non-dominant hand so that the fish’s ventral surface is facing upward and so that the fish’s head is facing towards you. Make incisions diagonally just anterior and posterior to the vent so that the two incisions meet dorsal to the vent (See figures 8a-8b). Some fish have a spiny projection posterior to the vent or the anal fins might be sharp so use caution when touching the area.
Step 9: Removal of Vent
If the incisions made have not allowed for the complete removal of the vent, firmly take hold of the vent and twist it to completely remove the vent (Figures 9a and 9b). If step 8 is done correctly, the vent should be able to be removed without much effort. The fish should look like Figure 9b at the end of this step.
Step 10: Locate Area of Incision to Be Made on Ventral Surface of Fish's Head
On the ventral surface of the fish’s head, ventral to the fish’s mouth, there is a “V” shaped patch of tissue that will be cut to facilitate the removal of the viscera. On some fish species, it is readily visible. On others (such as the mackerel that appears in these instructions), you must spread the gills to locate the area to be cut.
To do so, locate the gill covers and place the your index finger thumb in the gills (Figure 10a) and spread them out (Figure 10b). This should cause the ventral surface of the fish’s head that is to be cut to project ventrally, allowing for its visualization. Since the area is hard to visualize, this is one of the more difficult cuts to make for the inexperienced. See figures below to properly locate the area that is needed to be cut
Step 11: Making the Incision on Ventral Surface of Fish's Head
Place the fish on the bottom of the sink or on the cutting board and, while maintaining the gills spread open by keeping your index and thumb in the gills, take the knife and insert the point at one end of the “V” shaped patch of tissue that is to be cut. (Figure 11a) Continue to pass the knife through the tissue until it passes through the opposite side of the “V” shaped patch of tissue that is to be cut (Figure 11b). After the tip of the knife has passed through the opposite side of the “V” shaped patch of tissue, move the knife anteriorly until the “V” shaped patch of tissue has been cut. A new opening should have been made ventral to the mouth after this step has been completed correctly (Figure 11c)
Figure 11a. Shows the location of placement of knife to make the next cut. Location of cut is outlined in red.
Figure 11b. is a visualization of the “V” shaped area to be cut after the knife has passed all the way through it. Rest of cut is outlined in red.
Figure 11c. is a visualization of the new opening made as a result of successfully executing step 11
Step 12: Locate the Place of the Midline Incision
The next cut will be made along the ventral aspect of the fish, along its midline. The starting point will be the area where the fish’s vent was removed in steps 8 and 9 and the ending point of the incision will be at the base of the gills, just posterior to the incision made in step 11 (See Figure 12b). The incision should travel in between the left and right pelvic fins (Figure 12a). There should be a long opening in the place where the cut was made exposing the abdominal cavity of the fish. This opening will be used to aid in the removal of the fish viscera in step 15.
Step 13: Making the Midline Cut
Holding the fish in your non-dominant hand, take the knife and begin cutting along the midline of the fish’s ventral surface, moving anteriorly. Cut deep enough to get through the skin and muscular tissue, but not too deep so as not to risk the chance of cutting the fish’s viscera. Doing such could adversely affect the taste and quality of the fish’s meat when it is eaten later on. The incision should travel in between the left and right pelvic fins (Figure 13). Continue cutting anteriorly until you arrive at the posterior ends of the gills. There should now be an opening where the cut was made exposing the abdominal cavity of the fish. This opening will be used to aid in the removal of the fish viscera in step 15.
Step 14: . Insertion of the Finger Into New Opening Made in Step 11
Holding the fish in your non-dominant hand, take your right index finger and insert it into the new opening that was made on the ventral surface of the fish’s head in step 11 (not the fish’s mouth or opening made in step 13) (Figure 12a). Insert your finger deep enough so that at least half of it is inside the fish (Figure 12b. You may feel something sharp as you insert your finger into the newly made opening so use caution. This step is done to aid in the removal of undesired gills, viscera, and fins.
Step 15: Removal of Viscera
While the finger that was inserted into the new opening is still there, hook it so as to take hold of the fish’s viscera and gills. Use your other hand to grab the fish’s jaw to aid in the removal of the viscera (Figure 15a) Pull finger that is in the new opening towards the fish’s posterior end of the fish. The fish’s gills, pectoral fins, and most of its viscera should all be removed during this process (Figure 15b)
It can be hard to remove all these structures in one movement, but they can be removed later with the knife if needed. It might take several attempts to remove all the viscera in a single, smooth movement. Also, the freshness of the fish will affect how cleanly the viscera is removed in this step. A freshly caught fish’s viscera will usually come out easier than a fish bought in a store.
Step 16: Locating and Removing Remaining Viscera and Gills
At this point, the fish’s internal organs, blood, pelvic fins, and gills should no longer be attached to its body. If they are, they can be removed either by ripping them out or by cutting them out with the knife. Ripping out the remain internal organs is usually sufficient (Figure 16).
Step 17: 17 Location Removal of Undesired Fins
As for the remaining fins, ripping them out runs the risk of removing the fish’s meat as well, which is undesirable. They will need to be cut out with the knife to minimize loss of edible meat. The fins to be removed are the pectoral fins and the pelvic fins (Figure 17a). After removal, the fish should look like Figure 17c.
Step 18: Removal of Bloody Tissue Remaining in Fish's Abdominal Cavity
At this point, the fish’s abdominal cavity should be mostly empty with the exception of some bloody tissue that accumulates on the most dorsal part of the fish’s abdominal cavity, along the fish’s spine (Figure 18). Removal of the remaining bloody tissue will require you to run your thumb up and down the most dorsal part of the abdominal cavity, along the fish’s spine while water is running over the area. This can be done by holding the fish under a water faucet or by moving the fish back and forth in standing water as you run your thumb up and down its spine as described previously (Figure 18).
Step 19: Removal of the Head (Optional)
Viewing the fish’s side, locate the most posterior part of the gill covers (Figure 20a). These will serve as a land mark for the cut that will be made to remove the fish’s head. Moving dorsally from the posterior part of the gill covers, place the knife on the dorsal surface of the fish. This is where the cut will be made to remove the fish’s head (Figure 20b). Remove the fish’s head by sawing the knife back and forth until the head is completely severed from the fish’s body. After this step, your fish should look like the fish that appears in Figure 20c.
Step 20: Rinse Off the Fsh With Water
Rinse your newly cleaned fish off with clean, cool water to remove any debris left over from the rest of the cleaning process. The fish should look like the fish that appears if Figures 20c and 21. The fish is now ready to cook.
Step 21: Clean Up of Remaining Materials
All materials that came in contact with the fish should be washed thoroughly with warm, soapy water. This should reduce chances of contamination of other food products with raw fish and remove the “fish” smell”. If “fish” smell persists, consider using a more aggressive cleaning agent such as bleach.
Step 22: Giving Credit Where Credit's Due
Works Cited for Information in Introduction
EDF Seafood Selector. The Benefits of Eating Fish. n.d. 22 2 2018.
FAO. Global per capita fish consumption rises above 20 kilograms a year. 2018. 22 2 2018. .
NASA. Living Ocean. n.d. 22 2 2018.