How to Euthanize Fishes


Euthanasia is an unpleasant but sometimes necessary aspect of all animal health cares. Some scientists and vets have strongly criticized some of the methods widely used by aquarists to euthanize fish, saying they are slow and painful.

Euthanasia is used for two main purposes: to relieve the suffering of severely ill fish and to humanely destroy severely injured or deformed fish particularly fry.

There are several methods for aquarium fish euthanizing frequently utilized by hobbyists but only a handful is considered humane. Unfortunately, some of the methods previously considered humane have decidedly been determined not to be so. Here are a few methods considered to be a safe and humane method for euthanizing fish.

  • MS 222 is frequently used as anesthetic and a sedative for aquatic animals but in larger concentrations is the preferred method for euthanizing aquarium fish. It is approved by the FDA and considered humane by the American Veterinary Medical Association. It can be purchased through your vet or online. A bath with 250 mg of MS 222 per liter of water is adequate. The fish should be bathed for a full 10 minutes to assure death.

  • Benzocaine hydrochloride is similar to MS 222 and is a safe and humane method of fish euthanasia. A concentration of 250 mg per liter or more is effective for euthanasia. Contact your Vet for more information.
  • The active ingredient in clove oil is another sedative that when used in high doses are safe for fish euthanizing. It is not approved by the American Veterinary Medical Association but is considered safe and humane by most aquarists. It can be purchased at your local pharmacy or in most health food stores. Being oil, it does not dissolve in water. Once the oil is added to the water it must be shaken vigorously and the fish should be added immediately before the oil has the chance to separate. Dose’s greater than .25 ml per liter of water is adequate.
  • While this can be the most difficult for the fish owner, it is considered humane and is the quickest euthanizing method. Using a very sharp knife, detach the head from the spinal cord by cutting directly behind the gills. To avoid stress and discomfort associated with removal from the water; utilizing one of the above mentioned methods for anesthetization may be desirable

Filed Under: Pets & Animals

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About the Author: Fred Goodson has a passion for pets and animals. He has 4 dogs and is planning to have another one. He is also a blogger who writes about pets and animals. Currently, he is living in New Jersey.

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