Euthanizing Fish - Best Way?

[Kalinkacat]

This might sound like a stupid question, but I have an old Betta girl who is dying and was wondering what is the best way to put them out of their misery?  Is flushing the best way?

[matttimms49]

Sorry to hear that kalinakat. Unfortunately I'm not sure on the best way as I've not had the experience before but I'm sure someone will comment with some good advice.

[charlie]

Put her in a zip lock bag with some water and place in freezer.

[nerdRVT]

Please don't flush a living fish. Or freeze a living, awake fish.

You can euthanize most tropical fish with an overdose of clove oil. Clove oil can be attained at most health food stores, but it does not mix well with water (though it is okay at warmer temps), but mixes well with ethanol. I suggest diluting some in ethanol and mixing with water.

0.5mL clove oil per L of water is a good concentration. If you mix it with ethanol/etc, dilute accordingly. So, mix a mL of clove oil with 9mL ethanol, and add 5mL of the mixture to 1L of water for an effective dose. You can pre-mix larger amounts in ethanol and keep on hand in an opaque or amber glass container.

Bettas and other anabantoids can be tougher to anesthetize and euthanize via immersion because they have that labyrinth organ, and will take air from the surface if they sense something noxious in the water. When I have to sedate/anesthetize/euthanize bettas, I'll temporarily eliminate the air/water interface access for the animal until it is showing signs of sedation, and will not come to the surface to take in air. They will still become sedated and die even if you don't do this at the concentration listed above, but it will just take longer. Always put a lid on the container because the fish may try to jump. If you notice the fish is still taking breaths after 10-30 mins, add more of the clove oil mixture. Fish should be frozen after euthanasia (you don't see any breaths taken for 10+ mins) as a secondary method of confirming death.

This is a method we train people on for doing field sedation/anesthesia and euthanasia in fish, as it is safer and easier to prepare than other more common fish anesthetics.

[Dxpert]

Good info, thank you

[Black_Rose]

I use the clove oil method as well.

I've had to do it several times but only with zebra danios, guppies, and endlers.

[Kalinkacat]

Where do you buy ethanol?

By the way, the Betta died last night on her own but I know we have all been in this situation and thought that if there were a way to end it humanely, we would all like to know.

Thanks for the information.

[nerdRVT]

Canadian Tire sells ethanol.

You can mix clove oil with water at the temps we keep tropical fish at, but it just works better when mixed in ethanol, as it is an oil and doesn't mix as well with water as I'd like. Anything closer to 10-13C though, and it won't mix at all.

[bergenm]

I just put the clove oil in a container with some water, shaking it well will emulsify the oil and then gradually add the oil/water mix to the bucket with the fish. Add the mixture over a few minutes, the fish will slow and then stop breathing, I will usually overdose it at that point and leave it for an hour. You can freeze or add alcohol afterwards if you want to be really sure.

As was mentioned before bettas and gouramis can be more challenging as they can breath from the surface, putting them in a bag and removing any air will work in that case.

[th3budd]

If you're looking for Ethanol: check this link.

https://backpackinglight.com/forums/topic/78555/

[lucodu]

Finquel aka tricaine is supposed to be the gold standard for anesthesia and euthanasia for fish. (Source:  http://reefcentral.com/forums/showthread.php?t=2285518 )