Who can supply antibiotics, like metronidazole (trade name “Flagyl”), to fish owners?

I often receive requests to prescribe or dispense drugs by potential clients. I explain to them that as a veterinarian, I’m bound by regulation. Legally, Schedule 4 drugs (most antibiotics, including metronidazole) can be dispensed or prescribed by a veterinarian, only after they have seen the patient or inspected the establishment.

Some do not understand and often say that they know of aquarium stores that dispense such medicines. While that is common practice in the aquarium trade, it is not legal.

Below are reasons why veterinarians need to be involved when treating fish diseases, using drugs:

Some of these antimicrobials are important drugs that are used to treat human infection. The indiscrimate use of such drugs contributes to increasing the ability of bacteria and other microbes to resist the effects of a drug. Once antimicrobial resistance occurs, a drug may no longer be as effective in treating various illnesses or infections, in humans and in animals. Thus it is important to use these drugs only when medically necessary.

Another major reason why a veterinarian needs to be involved when dealing with drugs is that we need to ensure its safety. Almost all the drugs I use for fish in my practice are being used “off-label” (see tomorrow’s article on “off-label” drugs). It basically means that we’re using an approved drug in a way that isn’t listed on the drug’s labeling. Additionally, having the same active ingredient does not mean that it is safe for use in fish. For example, metronidazole comes in tablets and in oral liquid form. The liquid formulation designed for birds are not safe to add to fish tanks.

In terms of efficacy, we really need to know what we’re dealing with in order to prescribe or dispense treatment. It’s no use prescribing praziquantel if you’re dealing with a bacterial infection. It’s no use giving out oxytetracyline or doxycycline if you’re dealing with fish lice. Trying to treat fish diseases on a trial and error basis will waste valuable time and money, and many fish will suffer and die as a result. You need a correct diagnosis (see article on getting a diagnosis).

It is understandable that it is not always practical that veterinarians need to examine the fish prior to medication due to several reasons; mainly unavailability, expense and the short period between presenting with clinical signs and death – i.e. almost all fish diseases tend to be emergencies. But if you remember, if you’re on the vet’s books as a genuine client, and so long as the veterinarian is satisfied that their client knows how and when to use the medicines, all these practical issues can be managed. This is how it is done with clients in rural or remote areas.

To conclude, medically important antimicrobial drugs require veterinary oversight to be used for production purposes, and their use to treat, control, or prevent disease in fishes. To comply with the Veterinary Surgeons’ Board, a valid veterinarian-client-patient relationship (VCPR) needs to be maintained at least on an annual basis.

Did you know that you can access The Fish Vet’s services even if you’re not in Western Australia? With a solid background in veterinary pathology, histopathology services are also available. See article on fish autopsy.

You can contact me on the finer details of this service via email or the contact form on my website.

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Yours sincerely,

Dr Richmond Loh