# Thoughts on fish medication....



## acropora1981 (Aug 21, 2010)

My latest blog entry,

"Help my fish is sick!" Is a common cry for help from the novice aquarist. Of course, this call for help has led to a huge myriad of medications aimed at 'treating' diseases and sick fish. There is only one problem; they are frequently innefective. There are a number of reasons why medicating fish doesn't work, and of course there are situations where it most certainly does work, and should be used. 

Most of the science done on medicating fish has been done in the name of aquaculture, and not in the name of keeping fish for display. This is because aquaculture fish are usually in much more crowded conditions, and that leads to disease states much more quickly. There is also much more at stake, millions of dollars worth of food fish. The aquaculture industry has taught us however that fish are actually extremely difficult to medicate effectively once they are noticeably sick. 

The first problem is that once fish are noticeably ill to us, they are usually very far along in the disease process. Imagine if you had lesions on your skin, likely you would have started feeling ill long before these lesions appeared, and would have been hospitalized long before the disease got to that point. These outward signs are usually the only way we see our fish as being 'sick'.

The second problem is the delivery of medication. If you had a serious systemic disease, and someone rubbed some antibiotics on the outside of your body, probably you wouldn't get better. But this is exactly what happens when we put antibiotics into aquarium water. The medication is in the water, but not a lot of it actually enters the fish's body. The 'solution' to this is of course to put the medication in the food. However, if you've ever had a sick fish you will know that they don't generally eat much! That leaves injection. Injecting medications is very uncommon, except when keeping expensive pond fish (koi), where it does happen with some regularity. Injecting small aquarium fish however, is both impractical, and virtually unheard of.

Medications that we see for use in aquariums are generally used to try to save SOME fish out of thousands, not all of them. This is the final problem; straight numbers. Aquariums just don't have that many fish in them, and so even if you do medicate, you likely will only save a fraction of the fish in this way.

Of course, there are exceptions. External parasitic infections tend to be much easier to cure, as parasites are more sensitive than bacterial and fungal infections. Ich for example, in freshwater, is relatively easy to cure, providing you aren't medicating a tank with plants or invertebrates, and that brings us to the final point - medicating fish in tanks that contain more than just fish is nearly impossible. So called 'reef safe' or otherwise safe medications are orders of magnitude less effective than their harsh non invertebrate friendly counterparts.

So what is to be done with a deathly ill fish? In my opinion, culling, or euthanasia are called for in many cases with a fish that is very ill. The chances of saving the fish are so slim that it is a) more humane, b) less expensive and c) less stressful (for you and the fish) to simply euthanize the fish(es). 

In practice, I tend to medicate if the fish remains vibrant and feeding even with an infection. Shortly after the fish stops eating, and becomes listless, I euthanize.

Of course the aquarium industry would like for you to buy medication for every sick fish you ever encounter, but the reality is that most fish that become noticably ill will die, whether you medicate or not.

For most people, especially the novice, as soon as a fish is sick two things come to mind. The first is that if a fish is sick, it must need medicine. The second, of course, is that the fish store 'sold me sick fish!'. The fact of the matter is that pathogens (disease causing agents) are almost always present in our tanks. Fish kept in healthy, clean, low stress aquariums, are able to fend off disease. Fish kept in tanks with high stress conditions like overfeeding, crowding, agression, etc, are much more likely to get sick as they are weakened and cannot fight off infections. Without removing these condiditons, it is silly to medicate anyway, as the fish will simply continue to get sick even if the specific pathogen is removed. This is why the novice aquarist generally experiences more incidence of disease; their aquariums are often overfed, overcrowded, and very stressful for fish. The best medicine you can give your fish is good husbandry practices - quarantine new arrivals, do regular water changes, maintain filters, and feed appropriately, and choose healthy specimens at the store.


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## dl88dl (Mar 8, 2010)

acropora1981 said:


> The second problem is the delivery of medication. If you had a serious systemic disease, and someone rubbed some antibiotics on the outside of your body, probably you wouldn't get better. But this is exactly what happens when we put antibiotics into aquarium water. The medication is in the water, but not a lot of it actually enters the fish's body. The 'solution' to this is of course to put the medication in the food. However, if you've ever had a sick fish you will know that they don't generally eat much! That leaves injection. Injection medications do not exist in the aquarium hobby.
> 
> Very nice blog but in the Koi hobby injection of medications are a common practice


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## acropora1981 (Aug 21, 2010)

dl88dl said:


> acropora1981 said:
> 
> 
> > The second problem is the delivery of medication. If you had a serious systemic disease, and someone rubbed some antibiotics on the outside of your body, probably you wouldn't get better. But this is exactly what happens when we put antibiotics into aquarium water. The medication is in the water, but not a lot of it actually enters the fish's body. The 'solution' to this is of course to put the medication in the food. However, if you've ever had a sick fish you will know that they don't generally eat much! That leaves injection. Injection medications do not exist in the aquarium hobby.
> ...


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## blackninja (Dec 3, 2009)

I think the hobby has continued to advanced over several decades and many fish diseases have been identified/cataloged and remedial medication avaiable.
It is possible to effectively treat sick fish both from a preventive and curative aspect. But it is a science and most novices often wrongly diagnose the disease, recognize the problem too late, incorrectly apply the appropriate dosage/medication. There are situations where it is beyond the hobbyist to save the fish but they deserves credit for trying.


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## acropora1981 (Aug 21, 2010)

blackninja said:


> There are situations where it is beyond the hobbyist to save the fish


exactly, and I think that most infections, of a bacterial nature anyway, are beyond the hobbyist, which is what I'm trying to say. Most novices immediately turn to medications, when for the most part bad husbandry practices are what is the root cause. Combining stressful conditions with pathogens usually leads to disease, whereas healthy fish are often (but of course not always) able to fend off infection.


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## Cory (May 2, 2008)

While I do understand what you are saying and I do agree with much of it, saying that fish medications are usually ineffective isn't really a claim any one of us here can really make. I don't know of anyone on this forum who has done scientific studies on this sort of thing to be sure that in fact, the medicines aren't working. I think that more commonly the problem is inaccurate diagnoses rather than medications not being effective in treating what they are supposed to. When I've known what I had and treated it with the right stuff I've almost always had positive results. Fish are just so different from us physiologically that we have a hard time noticing when something is wrong period and then if so, figuring out what. I like to think I have a pretty good talent for pegging fish health and I can normally tell when something is off much earlier than others would notice it so maybe that is why I have had a more positive experience with medication. It's also probably the reason I never buy fish from Al's anymore, I can already see that most have SOMETHING. 

Another point of contention is to say that adding medicine to the water is like rubbing antibiotics on for a cold. It would be closer to taking an inhaler when you're ill than rubbing on a cream. Fish breathe and absorb various elements from the water through their gills and anything in the water can be absorbed into their systems far more effectively than if we were rubbing something on our mostly impermeable skin. Our lungs would be a much better comparison and inhalants are not ineffective drugs. 

All of this is not to negate your overall point which is that medicating usually doesn't work once the fish is clearly ill. Most fish diseases don't kill on their own, by the time the fish dies it has usually got 2ndary or tertiary infections that just drag it into the grave. Treating for just one, even if you treat correctly may not be enough. This not to mention that just like with humans there are infections fish routinely fight off with their healthy immune systems which when weakened will take hold and can be extremely serious (my grandmother died in a hospital this way from an infection she caught there but couldn't fight off due to a compromised immune system). 

The best advice I can give is to really watch your fish. First, it's good for your health (blood pressure and all) and second it's good for theirs. The more familiar you are with how fish, especially your particular fish, should be, the better you will become at noticing when something is awry. The quicker you catch it the quicker you can treat it. Also, always treat the entire tank. Hospital tanks are good, but by the time you move a fish out usually whatever it had is in the water anyways and you're gonna wanna get rid of it in the main tank too. Costlier but gives peace of mind.


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## acropora1981 (Aug 21, 2010)

some good points Cori;

However, there are a lot of studies about the ineffective nature of treating fish diseases. They litter the literature of aquaculture, and account for its extreme difficulty as a business.

Also, most antibiotics are not water soluble (ever tried to dissolve an EM capsule?), or are only somewhat water soluble, and so they are not effectively taken up via the gills. Also, gills were not designed to take up antibiotics, they evolved to take up oxygen, and release CO2 and some waste products, as well as regulate salt balance. Antibiotic uptake by gills is almost non existent, so my analogy is sound. Without appropriate cellular membrane receptors, things are generally excluded. There are no cellular binding sites for antibiotics.


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## dl88dl (Mar 8, 2010)

acropora1981 said:


> dl88dl said:
> 
> 
> > Yep. Once species. For viruses. In the pond hobby. Thankyou for pointing it out though
> ...


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## Cory (May 2, 2008)

Well, as far as I know, no organ in any living organism was designed specifically to take up anti-biotics so fish gills not being designed for them doesn't seem to make sense to me. As for what gills do, they are actually responsible for more than just gas exchange and waste excretion. Many essential nutrients are taken up by fish through the gills which is why for example you cannot keep fish in RO/DI water without adding key elements back into the water. It's also why ammonia and nitrite in high concentrations can do severe gill damage or why putting dilute clove oil into water will almost instantly kill a fish. Few substances I know of can kill a person in small doses when rubbed on the skin but a lot of gasses can kill us with only a little inhalation. 

As far as solubility goes, I don't know enough about antibiotics to say anything on the subject but I know most antibiotics I take come as capsules not liquids so you are probably right that there is only limited dissolution of those drugs into water or liquids in general. That said, a large portion of fish medications are not antibiotics and are very water soluble. Most medications for killing parasites are closer to selective poisons and anti-virals are a different breed as well. A lot of fish meds also work not by directly attacking the bacteria/virus but by causing physiological changes in the fish that make it impossible for the infections to persist. Some for example alter osmoregulation in the gills and starve oxygen loving pathogens or cause anoxic ones to be overwhelmed. 

One disease that does stand out though is MBD or myanobacterial disease also sometimes called fish tuberculosis etc. It is present in water everywhere, there are dozens or hundreds of different strains and there is almost no known effective means of removing it from water. In most cases it doesn't cause disease in fish because they are resistant to the type in their locale but if exposed to a new variant they are susceptible to, sudden unexplained death can occur or fish can slowly waste away and no treatment seems to work. I read a very scary article, I think posted by bae on this forum about this bacteria and it seems this would fit best with what you're saying because it is really a futile battle trying to combat MBD. 

I really wish there were a better icthyology program in the GTA, especially something at an undergraduate level or at least something that didn't have a biology degree as a pre-requisite so I could really study this sort of thing scientifically. It would be fascinating I think. Unfortunately, you need to live on the coast or be somewhere in the states or Germany to get a good easily accessible icthyology program and so I can't really comment on any of this with authority other than my own personal experience and readings. I'd love to read some of the articles on aquaculture that you mentioned, I've read stuff about salmon and other commercial fisheries potentially causing disease related problems for wild fish but not specific accounts of attempts to battle disease in commercial aquaculture. 

I guess what it really boils down to though is whether or not you want to give fighting the disease a chance or not. Euthanizing a fish gets rid of the sick fish but if the problem is contagious you're headed down a slippery slope with that approach which is why I prefer to try treating. I spent the better part of a year battling a myriad of diseases my bedroom display tank and upstairs hallway display tanks inherited from Big Al's fish I added without QT (biggest mistake ever) and after running the gambit of medications I finally won out over them all. There were losses along the way to be sure but the two tanks have been 100% stable with no losses for months now and I'm almost ready to start using the same tools for them I use in my fishroom lol.


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## blackninja (Dec 3, 2009)

acropora1981 said:


> exactly, and I think that most infections, of a bacterial nature anyway, are beyond the hobbyist, which is what I'm trying to say. Most novices immediately turn to medications, when for the most part bad husbandry practices are what is the root cause. Combining stressful conditions with pathogens usually leads to disease, whereas healthy fish are often (but of course not always) able to fend off infection.


Here is a list of bacterial diseases found in Aquarium fish. Red Pest,Mouth Fungus, Tuberculos - Mycobacteriosis, Dropsy,Scale Protrusion, Tail Rot & Fin Rot. Mostly treatable with antibiotics and mainly brought about by over crowding and poor water conditions all very preventable.
The antibiotics are mixed with their food so that it can be ingested. Fish too weak or sick to eat are symptoms of advance stage of illness, terminal to be precise. That is not the ineffectiveness of the medication but the hobbyist failure to recognize the problem and seek early treatment. The same happens in humans as well when the condition is too advanced for drugs to be effective.


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## BillD (Jun 5, 2006)

One of the problems with over the counter medications is that the prescribed dose is too small. This is a known problem and is a result of the manufacturers placating the FDA, in order to sell antibiotics over the counter. As an example, Kanamyacin, which is absorbable through the gills, is sold to be dosed at 150 mg per 10 gals. The dosage in the Tetra Manual of Fish health, is almost 3 times that. From my limited experience with it, it is the only antibiotic I have had any real luck with, and at the Tetra dose.
Clearly, the first thing that needs to be done before any dosing is a massive water change to remove as many pathogens as possible, giving the fish a much better chance and the medication a better chance of working. Massive water changes are often enough to allow the fish to fight the disease on it's own.


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## Darkside (Sep 14, 2009)

There are many medications that are water soluble and are used in aquaculture as well as in our home aquariums. I have to agree with Bill in that the main problem is how we administer the drugs to the fish. For example, when I treat large fish with fungal infections I hit the fungus directly with methylene blue and a Q-tip. I've used metro and clout to great effect. Seeing Tropheus swollen up like a balloon slowly deflate and return to normal after several rounds of concentrated clout baths will make anyone a believer. Whenever I bring in fish from the wild they are always treated for parasites with metro or clout and usually a G- antibiotic as well. I don't think the major problem with treating fish is ineffective medications, its improper diagnosis. It takes years to reliably diagnose fish maladies, usually more years than the average person stays with the hobby. If you can make a good diagnosis, you have a proper treatment plan and the appropriate space many fish diseases are easily treatable.


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## acropora1981 (Aug 21, 2010)

this is a great discussion  

I'm learning a lot here guys! Now I will edit my blog...

I think I'm still basically of the opionion that novice aquarists are better to cull or do water changes than to medicate, for a number of reasons, including inability to diagnose properly. Fish diseases present so similarily a lot of the time...


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## blackninja (Dec 3, 2009)

I have injected fish for various reasons and in most cases the dosage has always been dependent on the weight of the fish. This is especially true when administering antibiotics.


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