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How to Euthanize a Sick Fish

Posted on Tuesday, February 16th, 2010 at 11:36 am by

At one point or another, most hobbyists encounter a time when a fish is suffering beyond the point of possible revival. The question as to the most humane method to euthanize this fish often arises.  While there are several acceptable methods, we prefer using clove oil.

Clove oil is used as a fish sedative when performing procedures such tumor removal or general wound care. Clove old can be  purchased through many pond suppliers and health food stores.  A bottle should last you a lifetime….and if not…you should be reading many different articles!! 😉

The procedure is as follows:

Place the fish in a container of tank water at room temperature, and place the sick/suffering fish in this container. In a separate, smaller container, mix a solution of a bit of water and 3 to 4 drops of clove oil for every pint in the holding container.  Add this mixture to the holding container; this will be used as an initial dose, and will begin the process. The addition of clove oil to the water, slows down the fish’s breathing, and slows places the fish in sleep-like state.

At this point, you may add 3 or four more drops directly into the holding container. This will continue to slow down it’s breathing. After a about 30 minutes, you may add 3 or 4 more drops of clove oil to the container and continue to observe the fish for up to an hour or two. The fish should continue to slow down, until ultimately passing away painlessly.


  • Please take care with the doses and be patient in order to allow the clove oil to slowly perform it’s task.
  • Please keep Clove oil out of reach of children as it can be toxic.
  • Please dispose of the fish properly since clove oil can be dangerous to other animals if consumed.

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3 Responses to “How to Euthanize a Sick Fish”

  1. says:

    Hello! Thanks for that nice article. I never had to euthanize my fish (I must be lucky) so I never looked at how to do this. However, I thought using Co2 could be a good and human way to euthanize a fish.

    That would kill the fish for sure but would it be as human and efficient as I thought? What do you think?

  2. Greg says:

    This would probably not be humane as pumping the water full of co2 would suffocate the fish instead of sedate them. Think about how doctors help old folks go to rest sometimes… I know its a controversial topic but many times they use something like morphine to basically slow their central nervous system down enough to put them asleep and you know the rest.. I am guessing the clove oil does the same job. Please correct me if I am wrong anyone.

  3. Jim says:

    Greg, I agree with you about the CO2, and yes, the clove oil will sedate them “to sleep”

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