When a fish has to be put down

A responsibility that comes with it

Nobody wants to read this article, but it is part of keeping animals. Sooner or later most aquarists end up with a fish that will not get well again, and then it is good to know what to do before it is urgent.

Mattilsynet writes that a seriously sick or injured fish must be put down in a quick and painless way, and that as the owner you are responsible for learning how to do it properly, or for having it done by someone who knows how. Letting a fish die slowly in the aquarium is not the kind option, even if it can feel that way.

When is it right?

There is rarely a clear answer, but consider putting the fish down when:

• the fish has a disease with a poor outlook, such as dropsy with scales sticking out
• the fish has an injury it will not recover from, or cannot swim or eat
• you have treated it with no improvement, and the fish just keeps getting weaker
• the fish lies on the bottom or on its side, breathing heavily day after day

If you have not tested the water yet, do that first. Sometimes the water is what is sick, and the fish recovers after a couple of water changes. See Sick fish: how to spot it and what to do first. If you are unsure, a vet can help you decide.

How it is done

The method Mattilsynet describes is a blow to the head. It is quick, and done right, the fish loses consciousness at once.

1. Prepare, so it goes quickly once you start. Lay out a wet towel or paper towel on a steady surface.
2. Lift the fish out with a net, and hold it in the towel so it lies still.
3. Give one firm, hard blow to the head, just behind the eyes, with something heavy and blunt. The blow should be hard enough to stun the brain, but not so hard that the skull breaks. Do not hesitate and do not hit gently. A half-hearted blow is worse for the fish than a firm one.
4. With larger fish, you should also break the neck afterward, as Mattilsynet describes, to be sure.

It is not easy the first time, and it is fine to find it hard. The most important thing is that it is quick. If you cannot do it yourself, it is perfectly okay to ask a vet, a fish store or an experienced aquarist.

What not to do

• Do not flush the fish down the toilet, alive or dead. Mattilsynet writes that it can spread disease, and a live fish dies slowly in the sewer.
• Do not put it in the freezer or in ice-cold water. It takes a long time, and the fish can suffer for a long while before it dies.
• Do not leave it out of the water until it dies.
• Never release a fish into the wild, such as a stream or pond. It may suffer in water that is too cold for it, and it can spread disease to wild fish.

Afterward

Mattilsynet writes that dead fish should be buried or thrown out with the trash.

Always remove dead fish from the aquarium as soon as you see them. A fish left lying there rots and turns into ammonia, and if it got sick from something contagious, the rest of the fish can catch it. Test the water, do a water change, and keep an eye on the other fish over the next few days.

It is okay to feel sad. Many people grow attached to their fish, and a fish that has been around for many years is missed. Making sure it did not have to suffer was the last good thing you could do for it.