What the Beginning and Advancing Aquarist Absolutely Needs to Know and Do When Starting An Aquarium

What A Beginner Needs To Know About Antibiotic Treatments

This is a grossly misunderstood part of aquarium and pond keeping and is rarely presented correctly to the aquarist and pond keeper. 

There are two main kinds of treatments for bacterial infections -- chemical and antibiotic.  The antibacterial chemical treatments include the sulfa drugs, commonly termed sulfonamides.  These inhibit the growth and multiplication of certain bacteria, but do not kill them.  Because of their toxicity and increasing resistance of bacteria to them, sulfa drugs are of limited use in fish keeping.  The antibiotics are derived from microorganisms that inhibit or kill other microorganisms, particularly bacteria.   Antibiotics are not considered to be a cure for fish's bacterial infections.  Antibiotics control the growth of the infecting bacteria population in the fish, allowing the fish's immune system to eradicate the bacteria.

Antibiotics do not treat viruses, or single-celled or mult-celled infections.  Antibiotics are of limited use for treating fishes because none of the antibiotics have been originally developed for fishes, but were developed for man and farm animals.  Their requirements were originally quite different than for fishes, with only some being adaptable to be used for fishes.   The US FDA (Food and Drug Administration) has not approved any antibiotic treatments specifically for any aquarium or ornamental pond fishes, although this matter is now under review by the US FDA.  Presently, antibiotics can be legally used in the United States for aquatic animals if used only on non-food animals -- meaning that the fishes or other animals are not used for human food. 

Nevertheless, despite these limitations, there are applications when the right antibiotic is essential in treating certain bacterial infections of aquarium or ornamental pond fishes.  The problem is in knowing in each case what the bacterial infection is and which antibiotic is the right one to use.  There are not a lot of experts in aquarium and ornamental pond keeping who can really provide this answer.

Also, you need to know that increasingly the different kinds of infecting bacteria develop immunities to most of the antibiotics, so that using antibiotics involves finding out which one(s) work on the infecting bacteria, and which ones are totally ineffective.  When multiple tests are done on a bacterial infection of a particular fish or aquatic invertebrate to find out which antibiotic will kill the infection, it is common that the bacteria involved will be found to be immune to 15 or more commercial antibiotics.  This is not just true for bacterial infections of cultured fishes, but also true for wild-caught fishes and invertebrates.  The spread of immunity to antibiotics by bacteria in the natural environment, as well as in raised fishes and invertebrates is unbelievably widespread and rapidly increasing.  For example, those antibiotics that have been for years used on aquatics are essentially presently useless, such as penicillin and the tetracyclines. 

Most antibiotics that kill harmful bacteria infecting fishes, also kill off all the gram-positive beneficial bacteria in the water, including those that are essential to the beneficial "Nitrogen Cycle" and "Biological Filtration."  Most bacterial infections of aquarium and pond fishes are from gram-negative bacteria.  Therefore, the user needs to know whether the antibiotic being used is for eliminating gram positive bacteria, or gram negative bacteria, or both.  In diagnostic laboratory tests called gram staining this is determined by finding the bacteria's reaction to a special dye to show whether it has a negative or positive reaction to the dye.

In fact many commercial antibiotics are not suitable, being ineffective for use in water against bacteria, because the antibiotics are deliberately not readily soluble in water.  This is because the antibiotics are for human and animal oral ingestion, and remain insoluble until the internal organs do the dissolving.  If the antibiotics are added to the water, many will only moderately dissolve.  At best, for those antibiotics that do fully dissolve in the water, they will be effective for at most about an hour or less in the aquarium or pond water.

Therefore, be sure when using an antibiotic that is injected into the bloodstream of the fish, or put in the water, that it is in the soluble form, as well as being the right antibiotic for the infection.  An alternative is to try an antibiotic-containing fish food that is meant for ingestion by diseased fishes.  This is the safest way to provide an antibiotic, but there are drawbacks.  Usually the antibiotics used in fish foods are the traditional, long-available ones to which most fish-infecting bacteria are immune.  Also, fishes are prone not to eat when they are sick, so this has to be considered as well.

Another problem is when an antibiotic is used (such as erythromycin) that kills all bacteria, both gram positive and gram negative (but most effectively gram positive). That antibiotic destroys the "good" gram-positive bacteria as well as the "bad."  This can be a real problem for confined water conditions of an aquarium or pond.

One of the biggest problems when an antibiotic is used is that the aquarist or pond keeper needs to be sure that the treatment is continued daily full strength and through to completion.  If not, there is high risk that bacteria survive that are not killed.  Because of the exposure, they develop a resistance to the antibiotic.  Henceforth, the bacteria pass this immunity on in subsequent generations, and that antibiotic becomes useless in treatments on the bacteria's offspring.  Therefore, when using antibiotics, it is very important to treat through to completion of eliminating the bacterial infection.  Otherwise, the subsequent generations of the bacteria involved may have an immunity to the antibiotic used. 

Therefore, there is a lot of bad news about using antibiotics.  Use of multiple antibiotics in treatments can cancel each other out and be ineffective.  Excessive amounts can cause liver, kidney and other organ damage in fishes.  Antibiotics have no effect on viruses, or on single-celled or multi-cellular parasites.  Antibiotics that affect gram-positive bacteria are harmful to the beneficial bacteria in the water, including the biological-filter bacteria.  Without expert testing of the antibiotic on the infecting bacterium, it is impossible to know beforehand whether it will be effective or not as a treatment.  For most, this will require the services of a fish health expert and a diagnostic laboratory with the proper equipment to perform such tests.

Note that while Kordon's companion division AquaVet provides a line of antibiotics suitable for aquarium and ornamental pond use, they are not referred to in this beginner's article.  This is because the parent company Novalek is concerned about misuse of antibiotics by the general public.  In the interests of all concerned, Novalek limits the distribution of its antibiotic products to professional users. 

All of this gets us back to the beginning.  It is a lot easier to take measures that keep fishes healthy, than it is to treat sick fish.  Important considerations are:

         --   Take care in choosing the right fishes and to the extent possible see that they are not diseased. 

        --  Do not be rash in putting fish in with others before they have been thoroughly quarantined with preventative treatments to minimize the possibility of infection.   Take with extreme caution the advice from dealers that their fish have already been sufficiently quarantined.  Most dealer's aquariums are interconnected, readily passing infections one to the other.  Quarantining should be done by the aquarist before adding fish to a community aquarium.

        --  Use an organic herbal prophylactic such as one of Kordon's organic naphthoquinone treatments in daily treatments for all newly acquired fishes.

        --  Be sparing in the use of antibiotics to be sure that you are not doing more harm than good in their use, or avoid them altogether.

        --  Carefully observe the fish and aquarium conditions on a regular basis, preferably daily, to see that everything is trouble free.

        --  When adverse conditions are found, resolve them as quickly as possible, so that they do not get worse, making the conditions more difficult to resolve.

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