Clove Oil (Eugenia caryophyllata) is commonly used for sedation by hobbyists and professionals alike. It is used on food fish, bait fish, game fish, tropical fish and cold water species such as koi and goldfish. There are the usual arguments that since it is not "approved" by the veterinarian community it must mean something is wrong with it. This is simply not true.
I have used it on hundreds of koi. I know of many many hobbyists who've used it on their collections...some worth many thousands of dollars. All without issue.
I have also heard it rumored that someone used Clove Oil to sedate a fish and it never recovered. While this is always possible when dealing with sick or otherwise compromised fish I find it very unlikely that Clove Oil was the culprit. More likely it was a misunderstanding of how to apply it or an error in judgement as to how long a koi could be sedated before dying. Once a koi is sedated for handling using Clove Oil there is a fair amount of time for treatments to be administered before beginning the resuscitation process. The koi heart will beat for more than two hours even when deeply sedated. So although it may seem to be dead it is still very easily revived.
Clove oil at a rate of 12 to 16 drops per gallon will calm a fish in a matter of minutes. Larger koi seem to need a bit more to sedate them in a reasonable amount of time.
Add the clove oil to a small container of water which can be shaken thoroughly. Then add it to the sedating bowl. DO NOT LEAVE THE FISH UNATTENDED DURING THIS TIME. Use as few gallons of water as is necessary to cover the fish. Aerate.
When the fish lays over on your hand without flopping and while still having gill movement it is ready for treatment. Practice this a couple of times keeping a supply of fresh but aged water close by. If for any reason you feel the fish has become sedated too deeply, simply move it to fresh aerated water and assist the fish in using the gills and hold near aeration.
When the treatments are completed, assist the gills by moving the fish back and forth forcing fresh water to pass over the gills. Use your middle finger in the mouth with one hand and hold the tailstop gently with the other.
Clove Oil can be ordered from Essential Wholesale. Ask for Eugenia caryophyllata.
Their website is:
Their address is
Portland OR 97292