If the fish in the tank are seriously ill, it is more humane to kill them than to let them suffer. Freshly caught fish will also feel pain, but there are ways to minimize this and kill them quickly.
Step
Method 1 of 3: Preparing Fish for Euthanasia
Step 1. Ask your vet to do it whenever possible
There are many species of aquarium fish, many of which are unknown for the exact amount of drug dosage and other conditions. Veterinarians are trained to look for signs of whether an animal is suffering or not and can adjust the process if necessary, so that the fish does not suffer a painful death.
This article only discusses methods that can be done safely at home. Some other methods, such as lethal injections and electric shocks are difficult to apply humanely if you are not trained. In addition, the method can also harm the person who does it
Step 2. Find out your fish species
Immersion in ice or the use of certain medications can be humane to certain species of fish, but can be painful to other types of fish. The instructions in this article will provide you with the information you need to avoid making mistakes. However, you can get more concrete recommendations by doing an internet search about euthanasia (the act of killing living things to relieve suffering) of your fish. Most fish species have not been studied, but it can't hurt to try to find information, who knows what type of fish you have studied before.
Step 3. Keep the fish from getting too much interference from the surrounding environment
Place the fish in a quiet room. Cover the tank with something to prevent light from entering, or install a red light because the red color barely penetrates the water. This will reduce light interference on the fish, but still provide enough light for you to act.
Step 4. Do not feed the fish within 24 to 48 hours of administering the euthanasia medication
Unless it's already dying, wait for the fish to die without being fed during this time. Fish absorb euthanasia drugs more quickly if their stomachs are empty, and are less likely to vomit.
Skip this step if you want to use a method that doesn't require drugs
Step 5. Proceed to one of the methods below
All of the methods described below are humane ways to kill fish. Read the instructions carefully before starting. Not all methods are suitable for all species. The euthanasia bath method is not suitable for fish that are intended to be consumed.
Method 2 of 3: Setting Up a Euthanasia Bath
Step 1. Set up another tank or aquarium
Use a different tank unless you want to euthanize all fish in the tank. Take water from your current aquarium and put it in a new, clean tub, preferably with the same temperature and aeration. Fish can be stressed, or die inhumanely if you use water from another place or a different temperature.
- Some drugs, such as MS-222, can be ineffective at temperatures below 10ºC.
- Euthanizing a large aquarium is difficult, and requires measuring oxygen and chemical concentrations to obtain the ideal dose of drug. If possible, ask your veterinarian to perform this procedure.
Step 2. Try using MS-222
In pet stores, this drug is usually sold under the names tricaine methanesulfonate, "Finquel", or "Tricaine-S". Among various over-the-counter drugs, MS-222 is the most reliable drug. You can get them at pet supply stores. It is the only drug that has been approved by the FDA (US food and drug regulatory agency) for euthanasia purposes. Use 5 to 10 times the recommended amount for anesthesia (usually 250 to 500 mg/L).
Do not eat fish killed this way
Step 3. Avoid using alcohol
Many people think that alcohol can be used to euthanize fish without causing pain. This is not true. Alcohol can burn the gills and be very painful for the fish.
Using alcohol to kill fish is the same as when you euthanize humans by dipping them in gasoline. Don't do it
Step 4. Use clove oil carefully
It's quite difficult to know how concentrated clove oil is in a bottle, or even what ingredients are in it. This oil may just put the fish to sleep and not kill it. The fish are not safe to eat, and the used water should not be thrown into water sources because it can be dangerous. If you still want to use it, try the following methods:
- Put one drop of oil in the water and shake it until it becomes milky, then pour it into the aquarium.
- When the fish is lying at the bottom of the tank, make and add another solution by mixing 13 drops of clove oil in 1 liter of water (50 drops for 4 liters of water).
Step 5. Move the fish
Once you have added the selected drug, catch the fish in a net and immediately transfer them to the euthanasia tub. As much as possible do not hold the fish too long to avoid stress.
Step 6. Wait for the fish to die
Any euthanasia drug can put fish to sleep if used too little. The fish will die within 30 minutes, and you may have to wait up to 2 hours to be sure. Pay close attention to the signs of death below:
- The gills do not move for 10 minutes. (Usually after having a seizure for 1 minute.)
- The eyes do not move when the fish is shaken from the sides of its body.
- The heart beats very slowly. The heart can still beat when the fish is dead. However, a strong and relentless heartbeat indicates that the fish is still alive.
- If these signs do not appear within an hour or two, or if the fish wakes up again, add more medication.
- If you want to confirm that the fish is really dead, kill the fish using the physical methods below, or freeze them in ice water. It doesn't make the fish suffer if you have sedated it first.
Method 3 of 3: Physically Killing Fish
Step 1. Measure your own abilities and reactions
This can be a humane method if you can do it quickly and accurately. Use another method if you don't like seeing blood and dying fish. This method is usually used to kill fish for consumption or research subjects in the laboratory, not for pets.
If you are inexperienced with fish anatomy, do the exercises with the dead fish first so you can do them quickly and without mistakes
Step 2. Kill the small fish with a macerator
Fish that are less than 2 cm long can die immediately in the macerator because they are cut by a fast moving knife. Use a macerator that matches the size of the fish.
The larger the size of the fish, the more inhumane this method will be. Even if you have a macerator for a large fish, it can make them miserable
Step 3. Hit the fish to knock it unconscious (optional)
Stun the fish by hitting it just above the eye with a large, heavy object. Repeat with greater force if the fish is still moving. There is evidence that some species of fish can remain conscious when their heads are cut off. So, this is a highly recommended step.
Fish species that are accustomed to oxygen-poor conditions usually tend to remain conscious even after having their heads cut off
Step 4. Slice your fish
Press down on the fish's head and chop it off in a firm motion with a sharp knife, just behind the skull.
Alternatively, you can slice the back of the skull with a knife and sever the spinal cord and spinal cord of the fish. This "neck trim" is neater and less dirty, but it's not recommended if you don't have experience with fish anatomy
Step 5. Pierce the brain quickly
After the head is decapitated, the fish may be alive for a short time. Make sure the fish dies quickly by sticking a sharp nail or knife into the brain, which is between the eyelets of the fish. Move the spikes/knives back and forth to crush the brain and spinal cord endings.
Search the internet for information so you can figure out the most effective point for nailing the various species of fish that can be consumed
Tips
Fish that have been euthanized can spread disease or euthanize drugs that contain toxins. To dispose of it safely, burn the fish or bury it in a deep hole away from water sources, or wrap it in plastic or paper and put it in the trash. Do not throw fish in the drain
Warning
- Don't let the fish suffer because you rush to handle it and euthanize improperly. In low doses, some chemicals can make fish suffer pain without killing them. So, do this action properly.
- Make sure that your fish can't be saved or healed, or really suffer. Don't euthanize just because you don't want to or the fish has mild mildew. One example of a disease that makes fish eligible for euthanasia is tuberculosis.
- Do not use other methods without consulting your veterinarian first. Some of the inhumane methods include throwing the fish down the drain, letting it suffocate, and putting the fish in the microwave. Freezing and boiling are humane methods in some species, but can be very painful for others.
- Some fish may move erratically or energetically just before they fall asleep, especially when you use clove oil. This may (or may not) mean the fish is suffering. The drugs mentioned in this article are much less likely to cause this occurrence when compared to other drugs.
