Our mission

Euthanasia method?

Squist

Squist

Guest
BARcard
In the spirit of BAR's mission of "ethical husbandry", I thought I pose this: what is your preferred method of euthanasia of fish?

I looked through the site for know-how and, to my surprise, found very little regarding euthanasia. Last post was more than 5 years ago and there were just a handful. One by @Thales points to an article of his that's not longer available. Maybe a possible Reef Beef? "Reef Beef: unethical toilet flush euthanasia!"

I have (well, had) a fish that I had hand-fed attempting to nurse it back to health for a couple months. With success, I thought. But tonight found it struggling to breakaway from the overflow grate. I gave it a nudge. Still alive and could intermittently swim. But got pecked at by the others. It clearly was time.

So, I took it out of the tank and clipped his head off at the spine in one quick snip of poultry (fish tank) scissors. And I felt pretty good about the deed.

Got me wondering: how do others go about this?
 
Difficult topic; I applaud that you are bringing it up.

I don’t have a good specific answer for you, but in general as quick and decisive as possible would be best. Your decapitation method is probably one of the better ones. Similar methods are used in research for more humane ways to sacrifice other vertebrates.
 
Recommended procedure from AVMA:

Eugenol, isoeugenol, and clove oil. Whenever possible, products with standardized, known concentrations of essential oils should be used so that accurate dosing is possible. Concentrations required for anesthesia will vary depending on species and other factors, but may be as low as 17 mg/L for some species. Greater concentrations (10 times the upper range for anesthesia) will be required for euthanasia.298,313–315 These oils are not very water soluble; injecting the solution through a syringe and fine-gauge needle under the water in the container used for euthanizing is helpful in ensuring dispersal in the water. Fish should be left in the anesthetic solution for a min- imum of 10 minutes after cessation of opercular movement. These compounds are equivocal or known carcinogens according to the National Toxicology Program.316 Some studies in rodents indicate this group of anesthetics may cause pa- ralysis in addition to having anesthetic effects, and analgesic properties are unknown.70,317–319 The FDA strictly prohibits the use of clove oil and eugenol as anesthetics in fish having the potential to enter the food chain, except under Investigational New Animal Drug exemptions.320 Isoeugenol is a potential carcinogen316 so human safety in the application of that agent is of con- cern.
 
Thanks for starting a discussion on this. I struggle with this as well. I now use clove oil, but for years I did the freezer method which is recommended in a lot of articles. When I did further research on it though I swtiched as it turns out I thought I was doing good, but I wasn't.
 
CaseyP said:
I've used clove oil before and seemed to be pretty humane as long as you slowly drip in a solution of it. I got a small bottle of it from Sprouts in the essential oils aisle.
Click to expand...
I recently had to euthanize a neon tetra and used pre-mixed clove oil - was told to mix it in a small volume of hot water first, to solubilize it for rapid effect. Worked quickly, seemingly little struggle...
 
Bruce Spiegelman said:
Thanks for starting a discussion on this. I struggle with this as well. I now use clove oil, but for years I did the freezer method which is recommended in a lot of articles. When I did further research on it though I swtiched as it turns out I thought I was doing good, but I wasn't.
Click to expand...
What is wrong with the freezer method?
I had heard that was good, and that is what I do.
 
@rygh

S6.2.4 Unacceptable Methods The following are unacceptable methods of euthanasia in any situation. Flushing of fish into sewer, septic, or other types of outflow systems is unacceptable for many reasons. Water chemistry and quality may delay time to death and result in exposure to noxious compounds. For systems in close proximity to and/or connected to natural waterways, pathogen release or transmission may occur from diseased or carrier animals. Slow chilling or freezing of unanesthetized animals, including placing fish into a freezer without prior anesthesia, is also an unacceptable method. Similarly death by anoxia and desiccation after removal from the water or by anoxia in water; any death due to exposure to caustic chemicals; and death including prolonged traumatic injury prior to unconsciousness are unacceptable.
 
NanoCrazed said:
ice crystals can cause pain as water is still in process of freezing...
Click to expand...
Hmm. I am a bit skeptical on that specific problem.
They should be long deceased before ice crystals start to form.

But maybe they do feel the cold as pain like we do.
It is certainly not fun to take an ice water bath.
I know the old theory was that since they are cold blooded they do not have those type of senses,
but maybe new research proved otherwise.
 
rygh said:
Hmm. I am a bit skeptical on that specific problem.
They should be long deceased before ice crystals start to form.

But maybe they do feel the cold as pain like we do.
It is certainly not fun to take an ice water bath.
I know the old theory was that since they are cold blooded they do not have those type of senses,
but maybe new research proved otherwise.
Click to expand...

I was surprised myself but just trusted in what the vet experts wrote... i figured they would have more insights than I would. :)
 
So poking around for real science...
Before 2002, there was no real evidence fish perceived pain, and pretty vague until 2013-2016.

From this article: fish pain and a few others:
Fish perceive pain from caustic chemicals, intense pressure, and high temperature.
BUT is says specifically that Trout do not perceive cold below 4 deg C.
Which to me means: Fish have temperature receptors, feel cold, but probably do not experience real pain from freezing temperatures.
I could not find any others that even mentioned cold.

So .... I remain skeptical that freezing is particularly bad.
But since clove oil is pretty clearly better, that seems like the best way to go.
 
rygh said:
So poking around for real science...
Before 2002, there was no real evidence fish perceived pain, and pretty vague until 2013-2016.

From this article: fish pain and a few others:
Fish perceive pain from caustic chemicals, intense pressure, and high temperature.
BUT is says specifically that Trout do not perceive cold below 4 deg C.
Which to me means: Fish have temperature receptors, feel cold, but probably do not experience real pain from freezing temperatures.
I could not find any others that even mentioned cold.

So .... I remain skeptical that freezing is particularly bad.
But since clove oil is pretty clearly better, that seems like the best way to go.
Click to expand...
In AVMA guidelines it did say that if you were to employ freezing, it needs to have anesthesia and then instant freeze below 4 C or some point like that. What it recommends against is to freeze over time and without aid. Of course they also give a lot of other methods as well... some are not for the faint of heart.

"To ensure optimal hypothermal shock (ie, rapid killing), transfer of fish into ice water must be completed as quickly as possible. This means rapid transitions from acclimatization temperature to 2° to 4°C must be achieved. This can be accomplished by using minimal water volume to transfer fish (ie, using a net to place fish in chilled water). In addition, fish should not be in direct contact with the ice in the water; rather a depression should be formed in the ice slurry to expose the entire surface of the fish to the chilled water. Full contact with cold water ensures optimal exposure and rapid chilling of the fish. Water temperature must not exceed 2° to 4°C. Well-insulated containers, such as coolers, will assist in maintaining the ice slurry and a probe thermometer can be used to confirm water temperature. This method of euthanasia is not appropriate for temperate, cool, or cold-water–tolerant fish, such as carp, koi, goldfish, or other species that can survive at 4°C and below"
 
12 gauge works pretty well...

I joke, luckily I haven't had to deal with this before but I'm glad I have all this info now.
 
You must log in or register to reply here.
Back
Top