Goldfish Euthanasia
First of all, let’s make it perfectly clear that goldfish feel pain, and they remember it. They have a memory considerably longer than 3 seconds and are capable of complex behaviour.
So if a goldfish is suffering from an illness that cannot be cured or even treated, what is the best way of ending its suffering?
Some methods of goldfish euthanasia are based on anaesthetic overdose. Others are based on rapidly increasing carbon dioxide levels in the water, thereby suffocating the fish. Some methods use extremes of temperature. The old fashioned (and still widely used) way is to behead the goldfish.
Finquel
Finquel is an American brand name for a fish anaesthetic called MS-222. An overdose of this drug is considered a very humane method of goldfish euthanasia. The problem is getting your hands on MS-222 and administering the correct dose. It is also important to note that MS-222 makes water acidic. If this is not buffered i.e. if the acidity is not reversed, the fish will die a painful death. The easiest way to do this is to add baking soda in equal measure to the MS-222. Please note, this is unrelated to the baking soda method of goldfish euthanasia. The suggested dose is half a teaspoon of MS-222 with half a teaspoon of baking soda for every 4 litres of water.
Clove Oil
Using clove oil to anaesthetise a goldfish is a more accessible form of anaesthetic overdose. Indeed clove oil is also known as eugonol, a common fish anaesthetic used by vets. Fill a separation tank with 4 or 5 litres of the goldfish’s tank water and place the goldfish in it. Then fill a jam jar half full of the same water. Add a teaspoon of clove oil and shake it until the water turns white. This will require a bit of effort as clove oil does not mix readily with water so it needs to be shaken. Pour this mixture into the separation tank and wait for the goldfish to lose consciousness.
Isoflurane
Another veterinary fish anaesthetic that is not generally given to members of the general public because it is a substance that can be abused by humans.
Clove Oil and Vodka
A variation of the clove oil and water method. The idea is for the clove oil to dissolve in the vodka, which is then easily dissolved in the tank water. This method is not recommended because it is very hard to get the correct dosage. If it is not correct, the vodka burns the goldfish’s gills and caused extreme pain prior to death.
Baking Soda
When mixed with water, baking soda produces carbon dioxide. To use this method of goldfish euthanasia mix 10 teaspoons of baking soda with a litre of water then add the mixture to a separation tank with the goldfish already in it.
Alka Seltzer
Works exactly the same way as baking soda - it increases carbon dioxide levels in the water. Use one tablet per 10 litres of water, then add the goldfish.
When using any of the anaesthetic overdose or carbon dioxide poisoning methods leave the goldfish for at least ten minutes after the last sign of life.
Beheading
This is a quick and pain free method of goldfish euthanasia. Until relatively recently it was the only method. However, there are 2 good reasons not to dispose of a goldfish this way: firstly, the fish will experience obvious discomfort and stress in the moments between being taken out of water and getting its head removed, and secondly it can be very messy.
Freezing and Boiling
Do not use either of these methods. They are now thought to cause extreme pain and slow death.
Summary
So to get back to the original question - if a goldfish is suffering from an illness that cannot be cured or even treated, what is the best way of ending its suffering? There lies the problem. There isn’t a best way. For a start we are talking about killing goldfish. Never nice.
Anaesthetic overdose is, on the face of it, the most humane method of goldfish euthanasia. However on a practical level it may not be possible to obtain veterinary anaesthetic in a reasonable timeframe (or at all). The carbon dioxide methods are quite likely to cause a degree of suffering simply due to the fact the goldfish is being suffocated. It’s bound to know something is seriously wrong. The reasons against beheading are the same. Freezing and boiling are out of the question.
So the most important thing is probably not how the goldfish’s suffering is ended, rather how great that suffering is. If you know your fish is experiencing high levels of pain and discomfort and has a poor quality of life with no chance of recovery, you are doing the right thing by disposing of it humanely.