David Wallace, Surrey, United Kingdom.
A) The whole subject of livestock euthanasia has always been a sensitive one, creating very little regular and open discussion but nevertheless generating a great deal of strong feeling and disagreement whenever the topic is broached.
1) If the creature is clearly terminally ill, or
2) if it is already dying of old age and obviously in great distress. Ethically, there can be no other excuse.
Certainly the fishkeeper may be moving house and unable to take the fish with them, but that does not count as an acceptable reason to conveniently dispatch them down the toilet (incredulous as it may seem, it does happen)! In this particular scenario, if an aquarium has become too much of a burden, then the situation should be explained to a local retailer and the contents offered to them as a gift in return for a good home (if a payment is proffered then this can only be regarded as a bonus).
Likewise, destroying a fish or invertebrate because it is incompatible with other livestock, or just plain aggressive, cannot be excused. That is just plain cruelty. Even the culling of young fry could potentially open an ethical can of worms. For instance, is a fish of less worth, morally speaking, just because it is young? After all, if we culled young puppies, there would be a national outcry! Is there a fundamental difference?
The distinctive white cauliflower growths on the fins and body of a fish are a sure sign of Lymphocystis. While such a disease can appear temporarily most disfiguring, it is rarely fatal, and an extremely unlikely candidate for euthanasia. A Hermit Crab may not have moved for a few days and cannot be clearly seen inside the shell; however, this is a common occurrence after shedding the exoskeleton and again, no reason for the animal to be disposed of! On the other hand, a chronically distressed fish lying on the bottom of a tank, covered in white spots, with gills rapidly pumping water across infected membranes, may well be a candidate for a humane dispatch, especially if all other treatments have failed.
Unfortunately, there is no precise written criteria by which the hobbyist can decide at which moment to dispose of a badly diseased animal and most aquarists will have to rely on their own judgement. Of course, a vet could always be consulted to make the decision and they will also posses the drugs by which to quickly and painlessly kill the stricken animal, should it prove necessary. Financially speaking, most hobbyists would be unable to consider the services of a vet for this sort of procedure and have to make the final decision themselves.
Fish that have stopped feeding for some considerable time, are emaciated, in very poor condition and behaving abnormally are candidates for euthanasia; as long as all best efforts have been made to revive the stricken creature. In a case such as this, it may be very unfair to let the animal continue to suffer.
Sick invertebrates are, on the whole, much more difficult to cure as there are no specific medications as such. If improvements in water quality or lighting, or both, cannot rally a deteriorating specimen then a humane end might be the inevitable course of action.
So far, we have assumed that sick livestock, particularly fish, feel pain. Whilst comparatively little work has been done in this field, the general consensus of opinion by eminent biologists and other scientifically interested parties is that, yes, fish actually do feel pain. Therefore, any method of euthanasia must be quick and conceived to be as painless as possible.
2) Another related method adopted by professionals in the field of fish research for the EC demands that the spinal column is severed by a scalpel, or sharp knife, just behind the neck. Death is instantaneous and must approach being as painless as could be devised.
3) Powerful anaesthetics are available from a vet and these will, at overdose levels kill the largest of livestock quickly and painlessly. These can often be administered as a soluble addition to the water holding the fish in a suitable container. Vets will often want control over this procedure so don't expect to wander into a surgery and walk out with such potent drugs! Consult a vet who specialises in fish, as not all vets do. These may located in the United Kingdom by contacting the British Veterinary Association on 0171-636 6541 (other countries will have their own association). An added complication to this method is advice from the EC committee sitting on fish euthanasia requiring that fish should be treated in situ, as any travelling would undoubtedly distress the fish even further.
4) The fish should be put into a container full of tank water, to which has been added either several tablets of Alka Seltzer, some bicarbonate of soda or baking soda. All have the effect of increasing carbon dioxide to toxic levels, putting the fish slowly to sleep and ultimately resulting in death. The drawbacks with this method are
a) knowing just how much of the substance to use in relation to the size of fish, and
b) realising that it could take a great deal of time before the fish actually expires – hours in many cases!
Note: a method once thought very acceptable by most hobbyists and experts alike was to remove the fish to the refrigerator in a sealed container of tank water. Theory had it that the fish would slowly fall asleep and die as the temperature dropped and it all seemed very humane, especially for the owner! We now know that as the temperature drops, ice crystals form within the fluids of the vital organs long before death, creating what is imagined to be a very prolonged and painful period of suffering! Whilst this method is by far the most acceptable to the majority of owners (the out of sight, out of mind school of thought), in light of this new evidence, I don't think it can be realistically supported in future.
Seal up the dead animal within two, strong plastic bags (and a stout box if there are venomous spines involved) and take the package to the refuse tip and ask the attendant where best to dispose of it. Some authorities object to such matter being placed in a refuse sack, so check with the environmental health department first.
Note: resist the urge to bury the dead animal in the garden. If accidentally dug up at a later date, the fish bones, spines etc., may cause a nasty wound, especially to future owners who may be unaware that it is there.
Fish or invertebrate euthanasia is by no means a pleasant thought, but it is a job that must be done with the interests of the livestock as a priority; so, far better that the aquarist be prepared for what is an inevitable part of life than to cause unnecessary suffering by being unaware of the relevant facts.
The subject of aquatic euthanasia is one that understandably arouses strong feelings within the hobby. The above are my comments in the light of studying a draft report on the subject to the EC Commission. As hobbyists, your opinions are also important and can be passed onto members of the commission if so desired. If you have any opinions, please feel free to email me; although I cannot promise a response to each particular comment.