Euthanasia?

Question

What is the best way to humanely put a fish to sleep.

Pink Gourmi's chasing each other knocked off filter guard and one got stuck. It now has a huge hole in its side.

Answer 1

Euthanasia in Fish
By: Dr. Craig Harms

A Gentle, Easy Death

Euthanasia is the bringing about of a gentle and easy death, without pain or distress, usually for an animal suffering from a terminal disease. The word literally means an “easy and painless death.” An appropriate euthanasia technique should provide rapid unconsciousness followed by cardiac or respiratory arrest and ultimate loss of brain function.

In a culture where fish often meet their demise after a brief struggle at the end of a hook and line followed by slow suffocation out of water, euthanasia is not always a prime consideration for ending a fish's life, until the fish in question is an accepted family pet. The subject of fish euthanasia has received greater attention in laboratory animal settings than in veterinary private practice.

Euthanasia can be accomplished by an overdose of any anesthetic agent used for fish. These cause death by direct depression of the brain and vital centers. Larger fish that cannot easily be transferred to a bath treatment may have the anesthesia solution poured directly over the gills.

In cold-blooded animals, including fish, the heart may continue to beat for long periods after brain function has ceased, allowing for partial and somewhat distressing recoveries later if the fish is kept moist and cool. To be certain the euthanasia is complete, once the fish is deeply anesthetized and insensible, cranial concussion (a sharp blow to the head), decapitation (removal of the head), or exsanguination (bleeding out) may be performed to ensure death if heart function cannot be monitored.

Accepted Methods of Euthanasia

The American Veterinary Medical Association (AVMA) Panel on Euthanasia lists three acceptable methods of euthanasia for fish, and two conditionally acceptable methods. Methods listed as acceptable are overdoses with the anesthetics tricaine methanesulfonate (MS-222), benzocaine (related to MS-222 but less soluble in water) and barbiturates. Methods listed as conditionally acceptable are stunning (by a blow to the head) and decapitation in combination, or decapitation alone. Of the three methods listed as acceptable, tricaine and benzocaine are immersion anesthetics, while barbiturates are administered by intravenous injection. Overdoses of other anesthetics in water, such as eugenol (active ingredient of clove oil) and isoflurane (a volatile anesthetic used for gas anesthesia of terrestrial animals) will produce similar effects.

Hypothermia (chilling, freezing) is not considered to be humane when used as the sole method of euthanasia because the animal is not rendered rapidly insensible to pain or distress. However, freezing is an effective method of ensuring death of a fish and may be employed after the fish is insensible from an anesthetic overdose.

Euthanasia of Fish at Home

Bringing a fish to a veterinarian for euthanasia with standard anesthetics or euthanasia agents may not be practical in all circumstances. In these instances it is useful to have humane, rapid and effective alternatives to the toilet bowl. While flushing into the sewer system is almost invariably an effective means of killing a fish by exposure to intolerable water quality conditions, it is not necessarily rapid, and could pose the risk of introducing fish diseases to the local watershed. As mentioned above, stunning and decapitation together, skillfully applied, is considered a conditionally acceptable method of euthanasia for fish, in that it results in rapid and direct depression of the brain due to hypoxia. However, it is not necessarily an acceptable means when applied to one's own dying pet.

Clove oil, active ingredient eugenol, is being used increasingly in fish anesthesia, and is available from specialty food outlets and many pharmacies. Although it is not completely water soluble without first dissolving in ethanol (grain alcohol), particularly in cold water, enough dissolves to result in anesthesia and subsequent death at doses greater than 0.25 ml per liter of water (about 1 ml per gallon, or 1/4 teaspoon per gallon). Two anesthetic compounds which have been used in fish, but which are not recommended for clinical use due to difficulty in controlling anesthetic level and metabolic derangements they induce, are carbon dioxide and ethanol. Both of these compounds are often available in households when other potential fish anesthetic/euthanasia agents are not.

Carbon dioxide gas is listed as an acceptable method of euthanasia for terrestrial animals, causing death by direct depression of the brain and vital centers, but is not generally considered for aquatic applications. Carbon dioxide is released when Alka-Seltzer® tablets dissolve in water, and euthanasia can be induced with 2 or more tablets per liter (8 tablets per gallon). Ethanol (not rubbing alcohol, which contains a high percentage of isopropyl alcohol) can be used for euthanasia at a dose of 30 ml pure grain alcohol per liter of water (about 1/2 cup per gallon; note that ethanol content in beverages for human consumption is listed as “proof,” with 100 proof being 50 percent ethanol, 200 proof being 100 percent ethanol, and adjust dosage accordingly). Be aware that fish undergoing immersion anesthesia may experience a brief excitement phase as inhibitory neurons are depressed prior to achieving complete anesthesia. After the fish is insensible, these methods may be followed by decapitation or freezing to ensure death.

Answer 2

Having had to euthanize damaged or deformed (and obviously slowly dying from their deformity) fish, I've tried several of these methods and found that using Finquel is best. What I do is use a small ziplock bag, put only enough tank water to cover the fish, mix in a teaspoon of Finquel (more for bigger fish, it's a fish sedative, you can buy online, it's expensive) well, put fish in. It will go to sleep and never wake up. Then I put the whole bag into the freezer (toss them in the garbage after that). I've tried clove oil and had fish gasping at the surface for air because their gills get coated with oil (and yes they do eventually die). Vodka too I've seen fish go berserk, if only for a few seconds, before they die because putting alcohol on sensitive parts like eyes and gills hurts (like tossing alcohol into an open wound--or into your own eyes). In freezing, the fish (especially tropical fish) go through a long time of getting extremely cold before they die--not humane at all (it takes a whole for water to freeze). Flushing is horrible and should never be done--water is cold, if they make it through the pipes, the sewers are filthy, if the fish is sick there is the possibility that parasites and/or pathogens could be passed on.

Answer 3

Finding a humane way to kill a fish is difficult:
Flushing a fish would scare it and cause harm due to the chlorine in normal tap water.
Letting it suffocate by leaving it out in the air isn't humane.
Chopping its head off would be a quick death, but it's not something I would want to do.

A painless way of dieing that I have heard of would be freezing to death. The cold numbs your nerves so you don't feel it and you eventually fall asleep. If you could find a way of freezing the fish before it suffocated, then I believe that would be the most humane way of killing one.

The most humane way of killing a fish that I can think of would be to put it in a small container or cup and putting it in the freezer. The fish will slowly fall asleep and then die painlessly.

Answer 4

Cutting off the head would be a good way if only it did not involve taking the fish out of water and holding it down...

Two ways I've heard of seem like the most humane ways:

1. put it in a container of water and put the container in the freezer. Fish metabolism slows when the water cools, so it'd just fall asleep and would likely not go through the unpleasantness of feeling a need for warmth. We don't know. Anyway this way would be quick and peaceful.

2. put it in a solution of vodka (or straight vodka). This would be sort of like injecting a person with a large amount of pure alcohol - since the gills are in contact, the fish's body would absorb a large amount in a short time and it would rapidly anesthetize and kill the fish. I've never tried this but it seems like a good thing to try. I think I'd gradually add the vodka in case it caused the fish to freak out - like if it burned the gills and made the fish panic, I could quickly return it to the tank and try the freeze instead.

Answer 5

When I was working in a petstore they would make us separate dying fish, or fish with tumors, etc, and pour peroxide into their container.
It definitely kills them, and they don't put up a struggle at all.

I honestly don't know how humane it is, but taking cutting off a fish's head doesn't seem very humane, either, considering to do it quickly you'd have to remove the fish from the water, causing undue stress. Plus I couldn't even THINK about cutting of one of my fish's heads.. Ugh.

Answer 6

I don't think that flushing a live fish down the toilet is humane. Think of how scared the poor fishy will be in his last moments.

Why do you want to put it to sleep? I had a beta that was sick and couldn't swim or anything. I put him in a smaller bowl and gave him medicine. He died though,

Answer 7

Freezing is painless - the fish is no longer in any kind of concious state by the time the ice crystals do their damage.

Decapitating is painless - the stress of removing it from the tank and laying it out to be chopped is not painful to the fish.

Both these methods are valid as painless alternatives.

Answer 8

freezing causes pain in the fish as it's bodyparts slowly crystalise, i think thats not humane.
as for clove oil which many people recommend, i've heard of that not working as well.

there are "slow" ways to do it yes, but the quickest way is severing the spine or puncturing the brain, the fish will have to be out of water, but if it's done swiftly that won't matter. where as moving the fish from one container to another and then pouring some nasty substance on it and leaving it to die...i think that would cause more stress!

as long as when you remove the fish from the water, it's then put on damp newspaper and kitchen towel it will be fine. do it out the water, on the paper, and splat. all done in a matter of seconds.

if you can't bring yourself to do it, i'm sure you can find a friend to do it for you. i have several friends who just have no care for fish and wouldn't mind (gruesome cruel lot that they are!), and you may find a teenage male friend that would relish the opportunity hehe! i have another friend who always gets her son to do the deed when she needs to cull (she breeds fish).

Answer 9

It may sound gross, but a smashing blow to the head with a hammer is the quickest least painful way for the fish to die.

Answer 10

The best method is to put the fish in a small container of tank water and into the freezer. It will go quitely and fairly quickly.

MM

Answer 11

Here is a website with the most humane way, it also list the unacceptable ways at the bottom. http://www.wisegeek.com/what-is-the-most-humane-way-to-euthanize-a-fish.htm