Fish antibiotics – Updated 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.

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About Cynthia J. Koelker, MD

CYNTHIA J KOELKER , MD is a board-certified family physician with over twenty years of clinical experience. A member of American Mensa, Dr. Koelker holds degrees in biology, humanities, medicine, and music from M.I.T., Case Western Reserve University School of Medicine, and the University of Akron. She served in the National Health Service Corps to finance her medical education.
This entry was posted in Antibiotics, Fish antibiotics, Medical archives, Perennial Favorites, Stockpiling medications and tagged , , , , , , , , , . Bookmark the permalink.

24 Responses to Fish antibiotics – Updated 3-22-11

  1. Metals Chemist says:

    I am a chemist in the field of metallurgy and metal finishing. I have analyzed a fish-designated, 500 mg amox using my x-ray fluorescence spectrometer and have saved the spectral overlay display. I have also ordered a 500 mg amox which is designated for human consumption and will be analyzing it in the same manner, comparing their spectral overlay displays. I will then be analyzing the two capsules for NH2 (amino) and S (sulfide) concentrations, using a spectrophotometer. Normally, these meds would be analyzed using a GCMS, but I do not have one for my lab because of the line of work I am in. I will be posting the analytical results here within a day or two of this post.

    [Thanks so much, George! – Doc Cindy]

  2. Pluto says:

    Over two years later and still no definitive answer? Really?

    • Doc Cindy says:

      Hi Pluto, Thanks for keeping an eye on things.

      Here’s my conclusion 2 years later: antibiotics that are stamped with an imprint traceable to a respected company that provides USP AB-rated generics should be fine. Lacking this, you just don’t know.

      Doc Cindy

    • Tom says:

      I take fish mox for sinus infections. Haven’t noticed any adverse reactions…. save for my feet are now flippers, and I now breathe though my gills. I also have an unquenchable craving for water.

  3. Tina says:

    DJ – from which company/website did you order your fish antibiotics?

  4. RE says:

    Doc Cindy, something that you should be aware of is the program for smart phones called eppocrates. There is a free version (at least for android phones) and one of the great tools is a pill identifier. You indicate type of pill (capsule or tablet), shape, color, inscription, etc., and it’ll tell you what you are looking at if it is a Rx med. For the free version the prescribing information is light, but it is a great resource.

    [Thanks, RE – I don’t have a smart phone. I did google “pill identifier” and found several online programs including the one at: WebMD also has one. As long as we have computers and the internet, no problem!]

  5. Dr No says:

    [Doc Cindy prefaces a reader’s somewhat negative comment by saying: I do find some wisdom here, in particular the second paragraph below about doing personal research into the equivalency of an over-the-counter drug.]

    Anyone who posts their opinion on this (or any subject) based purely on “reading stuff on the internet” or how they feel about something is an idiot. Same goes for people who think it’s “just wrong” or for those who believe “it’s worth spending 200% for the SAME THING to be on the SAFE SIDE”. It’s either the same thing or it is not.

    I personally ordered “aqua doxy” and compared it with regular doxy I get from the local CVS. When I say “compared” I mean markings, opened the capsules, talked to the person who packed the capsules, discussed where they came from, who the manufacturer is, etc, TOOK the capsules, observed the effects, etc.

    Yes, I have a prescription for this, I just find it cheaper and more convenient to get the “aqua doxy” instead of jumping through hoops to use the “benefit” that my insurance provides me (while charging me an arm and a leg for the supposed “benefit”).

    I can tell you that it is obvious that it would not be economical to manufacture several different types of pills. I can also tell you that the pills I personally ordered are, in my opinion, exactly the same as the ones I previously bought from CVS and other local pharmacies.

    But don’t take my word for it. Be on the safe side, pay your copay. We need insurance companies to get even richer – maybe then they won’t deny as many claims and someone might get an operation they so desperately need approved. Nah, they’ll just pay themselves bigger bonuses, I think.

  6. D. J. says:

    I have purchased a considerable stockpile of various fish antibiotics. The product is promoted as USP grade and when the product arrived it was labeled USP grade. Comparing the fish amox with the “human” amox received from a pharmacy-looks like the same product-pills have identical same markings. I wrote to the company selling the fish antibiotic inquiring if companies manufacture antibiotics under a different “spec” for fish – dogs – human. The answer is –only one type is manufactured, it’s just labeled for different use to comply to the law. While I will continue to still purchase pharmacy antibiotics for the rare occasion my family needs them, I feel comfortable using the fish anitbiotics if {society collapses and there is no other option – ed. CK}.

  7. Frosty says:

    “If docs were convinced anthrax was in the air, we’d be making sure all our patients had Cipro available.”

    Not to argue Doc Cindy, but DHS/FEMA/CDC would be running the show if that were the case. Last time I checked, they have Push-Packs of medications that get shipped to infected areas with strict controls over who can draw from them. After treating those that are positively ID’ed as suffering from a particular disease, health care providers would be next in line to receive them, prophylactically, as they’d be coming into contact with infected patients. You wouldn’t be able to write RX’s for Cipro during an anthrax outbreak, and if you did the pharmacy wouldn’t be able to fill them.

    No offense, but I think you’re being disengenuous about these OTC ‘fish’ antibiotics. The FDA regulates all drugs sold in the US. Each must have unique markings for positive identification. The manufacturers list them as USP pharmaceutical grade. They are listed in the PDR.

    * * *

    [Doc Cindy replies – You’re certainly correct that the government would be running (or attempting to run) the show in the case of feared or documented epidemic, at least if the government existed. But I was seriously disturbed last year when the H1N1 scare revealed the inefficiency of the system. At least in our area, the vaccine did not reach us until well after the epidemic had past its peak, and had that virus had a higher mortality rate, hundreds or thousands in our area would have died. It seems to me that when chaos hits, the system may not be as prepared as they would have us believe.

    As for fish antibiotic identification, I expect this would be as difficult as identifying pills patients bring in and ask, “What is this little white pill?” Well, if it’s a brand name, I may be able to find it in the PDR (especially if I wrote the prescription and have some idea what it might be). But pictures of generics are not in the PDR, though there are other resource books with more pictures of drugs.

    In any event, I will look into the fish antibiotic question further and write another post when I have more answers. I don’t believe I am ‘disengenous,’ but I may be insufficiently informed to offer a complete answer. In a quick search of the medical literature I find no studies on the safety or effectiveness of using fish antibiotics in humans, and so the answer is based on extrapolation rather than true science. Stay tuned for more . . . ]

  8. Bruce C. says:

    No offense, but I find it hard to believe this veterinary antibiotic discussion is still not settled science. I’ve been reading this debate in various forums since pre-Y2k – and doctors, or those
    posing as doctors, make the same unscientific, unsubstantiated, and in many cases non-factual, claims in almost all of them. This article doesn’t appear any different, and as usual, seems to be based more on opinions than facts.

    For example (taken from the article and the comments above):

    “fish antibiotics are not regulated by the FDA, and therefore purity and safety cannot be guaranteed.”

    [I have amended the article to say “not regulated by the FDA for human use. – Doc Cindy]

    Not true. The FDA regulates all drugs sold in the US.


    “their safety is questionable”

    Do you have any links to studies or research to support your claim that veterinary antibiotics have a questionable safety record when used in humans? Millions of veterinary antibiotics have been sold in the 10+ years they’ve been available without a prescription, can you cite any research/news/reports where harm (or reduced efficiency, or mislabeling, or anything else) was caused by these drugs that would not have been caused by the same drug obtained from a drug store pharmacy?

    [All excellent points – but neither do I have evidence of their safety in humans. A veterinarian friend of mine says the veterinary and human antibiotics are all the same, at least the ones given to dogs and cats, but he wasn’t sure about the fish antibiotics. – Doc Cindy]

    and another:

    “I’m not sure pictures are sufficient to verify a fish antibiotic is identical to those given to humans.”

    Per the Federal Food, Drug, and Cosmetic Act (relevent section here:, each capsule, tablet, etc, must be UNIQUELY marked. Two “pills” with identical colors, shapes, and markings cannot, by law, have different ingredients. Has anyone ever heard of a poison control hotline inquire whether that oval white pill marked “pliva 334” that little Johnny just swallowed was a human one, or a dangerous fish one? Of course not, cause they’re identical.

    [I have tried looking up some of the markings on fish antibiotics and have not found them on the pill identifier sites. Perhaps someone would like to take on the task of finding the best pill identification site that lists the fish antibotics. – Doc Cindy]

    and another:

    “As long as a supply of human medication is available, I cannot recommend the use of fish antibiotics.”

    What exactly is the definiton of “human medication”? Does “USP pharmaceutical grade Amoxicillin”, for example, qualify? Cause that’s how the “Aqua-” variety are marked.

    Sorry, not trying to be argumentative, but if anyone has any links to studies or research that these drugs are not what they claim to be (ie, “Ingredients: Each capsule is X mg USP pharmaceutical grade Y” then please link to it! I stock (and replenish about every two years) most of the veterinary antibiotics that are available OTC. In every case, I’ve found them in the PDR (in the old days) or more recently on the web at sites like I have to buy them OTC, as no doctor is going to prescribe them in the quantities I desire (“hey Doc, would you prescribe me enough Cipro to treat a dozen people for inhalation anthrax?”). Let’s please get this debate out of the way so we can start intelligently discussing other topics regarding antibiotic use by non-health care providers in a post-Armageddon world, like “Pros/Cons of treating FUO with antibiotics” or “Antibiotic combination therapy – cause at TEOTWAWKI, you can’t afford to guess wrong)”.

    [I figure the definition of “human medicine” will change once the government is not in control. As a (government) licensed physician it is unwise to advise humans to use medicines intended for animals. – Doc Cindy]

    Bruce C.

    PS: Bonus question, why would Erythromycin for dissolving in aquariums have an enteric coating?!?

  9. Alan says:

    It’s easy to say not to use fish antibiotics if you are a MD and can write your own Rx to stockpile. Fish antibiotics don’t require a Rx. Are you willing to write a Rx for 100 ciprofloxacin?

    [Doc Cindy – under certain circumstances doctors do write long-term antibiotics . . . for travellers, missionaries, etc. If docs were convinced anthrax was in the air, we’d be making sure all our patients had Cipro available. If we thought the world was coming to an end for most of us, I expect we’d do so as well. For now, maybe you’d like to read How to get your doctor to help you stockpile medicine at

  10. GoneWithTheWind says:

    When I was a kid in the 50’s my friend had a dog and they feed it this dog food called “Myer’s horse meat” or something like that. We used to eat it out of the can and it was delicious. Big chunks of meat in a gravy. Ummm um!

  11. from Rob says:

    We are a long way from Kansas.

  12. CNA says:

    Thanks for an idea, you sparked a thought from an angle I hadn’t given thought to yet. Now let’s see if I can do something with it.

  13. CK says:

    I have used and stored fish antibiotics for years. Most are of good quality. Penicillin, Amoxicillin / Ampicillin, Erythromycin,Tetracycline, Doxycycline, Metronidazole, and some forms of Penicillin can be bought from vet supplies. . . Get and read a PDR. Many drugs can be bought for vet use which have a use in humans.

    • Doc Cindy says:

      As stated in my article, I would reserve these for true emergency use – when neither doctor nor human medicine is available – at least until I can verify safety and efficacy (if it’s even possible to do so).

  14. James says:

    I ordered penicillin and amoxicillin fish antibiotics and within minutes was able to locate the pharmaceutical company that made them and pictures which verified they’re identical to those given to humans. I promptly ordered more, because I believe in a serious emergency or system breakdown infection will be one of our greatest enemies. Next visit to the doctor I’ll ask about a supply of the blood pressure medication I take. Unfortunately, fish don’t seem to have hypertension. Probably all that swimming.

    • I’m not sure pictures are sufficient to verify a fish antibiotic is identical to those given to humans. I see lots of pills, and could not tell by looking at them exactly what they are. If there are any pharmacists out there, what would you say?

  15. Phil says:

    I’m looking at getting a supply of antibiotics to have on hand, for TEOTWAWKI use only. I was debating going with “the fish” or with an overseas supplier. Thanks for clearing things up.

    My problem is my doc died…. 20 years ago. I’m healthy for the most part, went to the doc for something the first time last year, a back injury…. had to pick the Doc from the local clinic.

    It’s true, there are $4 prescription antibiotics… if I pay $75 for the Doc visit, and can convince him that I would like to have on hand a good supply of antibiotics on hand, just in case TEOTW happens. A big gamble. I’ve read your article on Doctor/Patient trust and TEOTW concerns. If only I had the extra cash to make half a dozen visits. My plan so far is to get a wide spectrum of antibiotics and up to date information from the web printed out on each one. I already have up to date copies of the PDR, and other manuals. I wouldn’t think of using them, unless things were bad, and medical problems were present. {I don’t use them now, even when I should… figure I should build up as much resistance to whatever whenever I can… as long as the ‘system’ is there for backup. }

    • As Phil points out, cost is an on-going concern for many. Of course, the price of fish antibiotics is also greatly inflated and their safety is questionable. If doctors knew that the end of the world were coming, we’d be doing all we could to prepare our patients. Lacking direct evidence, the question becomes stickier.

  16. Tim says:

    Thanks for shedding some light on this topic.

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