**(by CP) : ** “I’ve seen arguments on my fish hobbyist sites against icewater.”
I have tried ice water, freezer, and heaving them out onto the yard when it’s around zero F. I wasn’t impressed that the icewater or freezer were particularly instantaneous; the yard one was pretty much a goner at the time of disposal. I myself dislike jumping into icewater. I think it hurts, and it is certainly not an instantaneous death. Of course all of this anthropomorphizing has a fair amount of speculation. Here are a couple of equally speculative, potentially unsound, and completely unscientific opinions of the type I was talking about. I myself am probably too calloused to fret over any method, and certainly too cheap to do some sort of anesthetic method. On the other hand, my calloused method of sending them down the disposer is definitely instantaneous and unambiguously discomfort-free. I’ve been a pretty successful hobbyist with my African Cichlids, so I don’t have too much personal experience with putting them down.
Burgess et all (1998) do not recommend the use of ice or freezing water to euthanise fish, but Brown (2005) specifically describes a process that is acceptable for very small fish (under 5 cm in length). The fish is either (a) exposed to freezing cold water but is not in contact with the ice itself; or (b) placed in a container of normal temperature water from the tank and then that container is transferred to a freezer where it can cool down to below freezing."*
From http://www.nippyfish.net/euthanasia.html (Oddly, the title has nothing to do with the discussion of the method…)
"*Unacceptable Methods for Fish Euthanization:
Freezer Method:
Dropping your fish into freezing ice water or putting them in the freezer to slowly freeze (hypothermia method) does not quietly put your fish to sleep. In cold blooded animals, it is believed that the formation of ice crystals in the tissue may create discomfort or severe pain. The hypothermia method is never ok. Rapid freezing may be applied only if the fish is deeply anesthetized prior.*"
When managing a fish room, anything we needed to euthanize immediately we slammed against a counter top in a net. Instantaneous.
With fish at home, where I was likely to have more time, I used the freezer method. Fish in tank water in plastic bag, to cool down and freeze. The theory being that as the fish’s body temperature dropped, their metabolism slowed and their “awareness” decreased, well before the formation of any ice crystals. At least, I never got a complaint. Used the same method with reptiles.
For me, the clove oil method has always worked well. I found clove oil in a toothache remedy medication at the local pharmacy, I put it in a small container with some water, shook it very well to get the clove oil to mix with the water, and then put the fish in the container.
Once the fish is clearly non responsive from the clove oil, then I freeze them (because my belief is that freezing could potentially be painful, I would not want to do it while the fish was still aware, but it seems like a good way to ensure the fish won’t wake up).
Some people don’t sympathize much with fish because they seem so different from humans, but from watching their behavior I am convinced they are capable of suffering when they don’t feel well. I feel we owe it to any animal in our care to try to give it the most humane death we can.
I see lots of recommendation for alcohol such as vodka, but wouldn’t rubbing alcohol be a better option both in terms of cost and function? It’s a cheaper product with higher concentrations of alcohol.
(Note: I know that some rubbing alcohol is isopropyl rather than ethyl alcohol. I’m not sure if that makes a difference).
Out of all the “old-school” methods, this process seems most inhumane. The AVMA (American Veterinary Medical Association) does not advocate freezing fish as an acceptable method of euthanasia; the only way they would approve of cooling would be to deep freeze an animal that is already under deep anesthesia.
Decapitation - Swift and Surely
This method is self-explanatory – you simply remove the fish from the water and use a sharp knife to chop off its head, thus ending its life. The fish might feel something as you slice the knife in; even it is momentary pain. At least this method is quick (as long as you do not hesitate once you start the task). The AVMA believes that this can be acceptable as long as it is coupled with anesthesia to begin with.
Carbon Dioxide
Carbon dioxide is naturally present in the water your fish live in anyway – it is a result of the respiration process. It can also be used as a method to euthanize fish because the addition of carbon dioxide to the water decreases oxygen levels, thus causing your fish to suffocate. Alka Seltzer is a popular source for carbon dioxide to be released in water. This method may seem innocuous enough, but most people who have used this method say that their fish thrashed around a little bit just as if the fish were out of water (here is one person’s story). You may need to decapitate or freeze the fish afterwards to ensure death. The AVMA supports this method and many universities advocate using this method as well (see the University of Washington’s Policy for Euthanasia for Fish Species). Dr. Craig Harms (http://www.petplace.com/fish/euthanasia-in-fish/page1.aspx) describes this method; 8 tablets of Alka Seltzer is required per gallon of water.
Despite what Gill said in Finding Nemo, all drains (and toilets) do NOT lead to the ocean.
Instead, all sanitary drains lead either to a wastewater treatment facility (WWTF) or a septic system. The solids at a WWTF end up being incinerated or sent to a landfill.
I’ve given some thought to the problem of quickly killing fish, as I do a bit of fishing myself. The common method for medium-sized fish (like perch) around here is to break the neck of the fish. This certainly paralyzes the fish, but does it kill them fast enough? Remember, fish don’t breathe like mammals, and are not dependent on nerve impulses to the body to keep the blood oxygenated. It seems to me like breaking the neck would add pain rather than shorten it!
My own preferred method is to stick a knife through the upper part of the eye socket into the brain and give it a couple of twists. Is this good enough, or is there an even better way?
(I guess smashing the head with a hammer would be even faster, but it makes filleting hard…)
Fish don’t have necks… but I’m assuming you mean a technique of bending and breaking the spinal column near the back of the head?
Not sure what this means. Fish don’t breath air, but they do respire none the less (by passing water over the gills). And yes their respiration system does use nerve impulses and oxygen level sensing to function.
The fish described in the OP 7 years ago was about the size of a large coin, so physical trauma to kill it would certainly work, but you’d essentially just splatter it with a hammer like a ketchup packet. A seemingly more humane way to go would be to use clove oil. But the chasing with net and stress of moving the fish to a little “death chamber” container where you’d give it the happy juice mixed with a bit of water would probably negate the benefit. Yeah, just net a little fish out and smash it with a small blunt object; even step on it - if you can go from tank to dead on the floor/countertop in 5 seconds or less you’re good.
For larger angling size fish, use some sort of club to smack the fish on the back of the head. It can be as crude as a piece of wood or plastic pipe, a foot or 2 long will be enough to kill most fish. No need to risk cutting yourself or use precision twisting techniques.
