How Should I Euthanize This Fish?

[nmonks]

This does not cause ice crystals as they die quickly and are not frozen.

This is actually controversial, and I'd encourage you to peruse the scientific literature on the topic. A fair summary is this, from the Cornell Center for Animal Resources document on Fish and Amphibian Euthanasia:

"Thermal shock (freezing) - This method is controversial, as some believe that as ice crystals are formed, the animal will feel pain; however, in small fish (e.g., zebrafish*) it appears that they die rapidly before the ice crystals form."

In aquarium books written by vets and fish health experts like Peter Burgess, you'll typically read something along these lines, taken from the "A-Z of Tropical Fish Disease and Health Problems":

Unacceptable methods of euthanasia … plunging them into iced water [or] slowly chilling them (with or without water) … note: this method is still commonly advocated in the aquarium fish literature, but is now considered to cause the fish unnecessary pain.

I confess I used to use the iced water method for euthanising fish, but exposure to scientific methods (and welfare standards) at university followed by more reading around the topic has convinced me the iced water method is obsolete. Clove oil is so cheap and so easy to use, that if we can see that it's painless, and the vets seem to agree that it is, then it's something all aquarists should consider. There are a few caveats, like how to deal with large air-breathing fish (best advice: contact a vet) but it's still the easiest, most humane, and least-expensive mode of euthanasia I'm aware of.

Cheers, Neale

*Zebrafish are what we hobbyists call danios.

 

[Katty]

Thanks for all your comments. Anyways, I went with the quick dunk into ice-water and it was dead within a second

Rest in peace little fishy

 

[FishFanatic04]

RIP

 

[gforce17]

Flush it down the bog

So English, I love it! but not a good thing to do!