Fish antibiotics – Updated 3-22-11

Fish antibiotics . . . . . . are they safe? . . . are they effective? . . . are they the same ones used to treat humans? 3-22-11...
Chrysiptera parasema, commonly known as the ye...

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Fish antibiotics . . .

. . . are they safe?

. . . are they effective?

. . . are they the same ones used to treat humans?

3-22-11 UPDATE:

This question is harder to answer than you may think, though I keep working at it when I have a little free time.  I have identified one source of fish antibiotics that I believe may be selling the same medications used in humans, but this will require further verification.  Keep posted for further details.

* * *

Original article continues . . .

These questions have been submitted repeatedly by preppers and survivalists.  In checking online pet-supply sites, it is true that fish antibiotics are available for aquarium use without a prescription.  Some of these sites list off-label dosing recommendations  for pets such as cats and dogs.  They also state “Not for use in humans.” 

Fish antibiotics include ampicillin, amoxicillin, cephalexin, tetracyclines, erythromycin, penicillin, metronidazole, and sulfamethoxazole+trimethoprim, as well as the anti-fungal drug ketoconazole.  Generally speaking, the milligram amount of these tablets is of the strength also used in humans.

Why would the same drug for fish be labelled “Not for use in humans”?

A variety of reasons come to mind.  First, it is unlawful to purchase these drugs for human consumption without a physician’s prescription in the U.S.  Giving them to another person would be practicing medicine without a license.  Secondly, fish antibiotics are not regulated by the FDA {for human use}, and therefore purity and safety may not be suitable for human use.

Staphylococcus aureus - Antibiotics Test plate

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Here’s an analogous question:  would you eat dog food? Munching on a Milkbone might not be too objectionable, but I can’t see myself chowing down on a can of Alpo.  (Though who knows . . . if it’s a choice between Alpo and road kill possum, I might go for the Alpo.)

As long as a supply of human medication is available, I cannot recommend the use of fish antibiotics. Perhaps a chemist out there would like to tackle the job of analyzing a certain line of fish antibiotics for impurities.  This brings up another question, whether stockpiling fish antibiotics might yield a supply of, shall we say, crude antibiotic preparations, that could be further purified by a trained chemist (which I am not). Another question is the manufacturing source of fish antibiotics, which I do not know.  It’s possible some are made by the same companies that make human antibiotics, which are then re-labeled for aquarium use.  Considering the mark-up on fish antibiotics, this would not be an unreasonable thing for a pharmaceutical company to do.  For human use, each of these antibiotics is inexpensive and most are on the $4 list of prescription medications at discount pharmacies ($4 for about a 10-day human supply).  For example, Wal-Mart offers 30 tablets of cephalexin 500 mg. for $4, whereas online I find a price of $21 for the equivalent drug for fish.  When my son took his dog to the veterinarian recently he was charged $42 for the same thing.  It really makes more sense to use human antibiotics on pets rather than the other way around.

If modern civilization were to end and my daughter was dying of pneumonia, would I treat her with fish antibiotics?  Probably so.  If she had a sinus infection today, would I send her to the pet store to save a visit to the doctor?  No. For those looking to stock up on antibiotics, I suggest reading my entry on “How to get your doctor to help you stockpile medicine.” Human medicines, that is.

I can’t argue with stockpiling fish antibiotics, with the hope of further purification, for interim use until the manufacturing process has been re-established.  I have contacted two chemists about the possibility and await their reply.  In the meantime, learn about preventing infection at: .  If I am able to confirm that any fish antibiotic products are actually repackaged human products, I will let you know.  However, that does not make them legal to purchase for intended human use.

Drawing of male freshwater phase Chinook (king...
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