This is what I choose to do with my fish and my comments are only placed here as opinion. This is a heated topic. I choose based on my knowledge from my training:
Oil of cloves is a topical anethestic and was used in the past to treat toothaches. Lidocaine (like at the dentist's office is a topical anesthetic as well). When we operate on people we really want to achieve 2 things, analgesia and anesthesia, that is, relief of pain and unconsciousness. IMO, when a fish is immersed in oil of cloves, it is essentially 'topically anesthetized', paralyzed, but, I am NOT convinced that the fish is unconscious.....none of us will really know for sure. We don't know if the oil of cloves causes stinging to the mucus membranes, eyes, etc on initial contact nor if the fish is motionless, painless but aware.
Extreme cold is an anesthetic. When applied to skin, you can actually cut the skin and feel no pain. Cold also can cause rapid unconsciousness. In fact, hypothermia is reported to cause a state of euphoria and clouding of consciousness. Fish, at least most of the types that we keep (tropical), are extremely small and rapid immersion in extreme cold water, in my opinion, causes rapid pain relief and rapid unconsciousness. I have never seen any of my fish shows signs of what I consider suffering. They stop moving immediately and appear lifeless. Some have stated that since fish are ectothermic, this doesn't apply....perhaps in cold water fish I would agree.
I choose to euthanize my fish this way, rather than oil of cloves. One must either make an educated decision for themselves, or, choose what is currently accepted by the masses as what is humane.
Added: although I would never use blunt force to euthanize my fish, nor advocate it, one fact is for sure: death is instantaneous
SH
