- put enough tank water in a container so the fish can swim upright. Count how many litres of water you are using.
- prepare an emulsion of clove oil and tank water in a bottle. Use 3 drops of clove oil per litre of water you have in your container/bucket. Shake the bottle so the water turns a milky colour.
- put the fish in the container. Slowly add the contents of the bottle. After about 30 seconds (depending on the size of the fish), the fish should sink to the bottom and you will notice your fish's breathing is much shallower.
- Leave your fish in this container for at least 20 mins. This ensures full anesthesia.
- After that, you can either transfer the container to your freezer or you can add vodka (20% of the water volume) to kill your fish.
Notice that clove oil is classed as a poison, so you should avoid direct contact. I bought a small bottle from a pharmacy for $13.