Aquarium Medications Part 2 | Antibiotic & Antimicrobial Treatments
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By Carl Strohmeyer-PAMR 40+ years experience
TRIPLE SULFA (Sulfamerazine, Sulfamethazine, Sulfathiazole) & Other Sulfa Based Medications:
Sulfas are considered all anti-bacterials (antimicrobials).
Sulfa drugs arrest cell growth by inhibiting the synthesis of folic acid, a component required for growth by bacteria. Folic acid is a large molecule and is unable to enter bacterial cells, so the bacteria must synthesize the compound intracellularly.
Sulfa drugs are among the oldest in the medicine, the first being a sulfonamide was trade named Prontosil dating back to experiments by Bayer in 1932.
USE: A relatively broad spectrum antibacterial medication; for fin and tail rot, mouth fungus and clamped or collapsed fins, Columnaris (mild to moderate infections ONLY), and hemorrhagic septicemia (although not effective to Aeromonas infections of the gut).
Triple Sulfa is often a good choice when there is an infection caused by a scrape, abrasion, or similar. While not often the first choice for fish eye issues, including pop-eye, it can be a first choice or a second choice if the first choice fails in treating such maladies involving the eye. This would not only include and in-tank treatment but use as part of a "Fish Bath" treatment too.
An old standby that is still useful and can be used in combination with Malachite Green (especially effective in combination with MG at ˝ strength when treating Ich in scale less fish) or Acriflavin (do not combine with copper sulfate).
It is noteworthy that Sulfas are more effective at higher pH levels which is an important point for many fishkepers.
How to treat: Fin Rot in Bettas and other Fish
Sulfas can also be safely used with other mild broad spectrum parasite/fungal treatments to boost anti bacterial effectiveness,; a good example would be the Medicated Wonder Shell.
Product Reference: Medicated Wonder Shell
DOSAGE: 250 mg per 10 gallons every 48 hours (24 hours for severe issues) with a 25% water change before each treatment. Treat for a minimum of 10 days.
Sulfa is found in (Recommended place to purchase to support this free information):
*Best not used concurrently with other antibiotics/antimicrobials, although use with chemical dyes such as malachite green is safe and even advised.
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Trimethoprim is a bacteriostatic antibiotic effective for many aerobic gram negative bacterium including Pseudomonas & Aeromonas.
Since Pseudomonas & Aeromonas are common causes of opportunistic fin rot in fish (assuming the causes of this opportunity are negated), this drug or a combination that includes it may be a good alternative treatment.
However Trimethoprim has no proven effectiveness for anaerobic infections, so if the causes of an Aeromonas is anaerobic (which most are), then this or antibiotics containing Trimethoprim would be a poor choice.
USE: A good alternative to 100% sulfas, although a more harsh antibiotic toward nitrifying bacteria.
*Can be very harsh to nitrifying bacteria in an aquarium, do not over dose and use only in well established aquariums.
Trimethoprim is found in (Recommended place to purchase to support this free information):
USE: Tetracycline is the name of a large class of antibiotics produced by Streptomyces bacteria.
Tetracycline Hydrochloride is a naturally occurring Tetracycline used in the treatment of bacterial infections that are generally gram-positive such as Streptococcus and SOME gram-negative infections in fish.
Tetracycline Hydrochloride is generally more effective for aerobic bacteria (which Columnaris is only aerobic however Aeromonas and many other pathogens can be anaerobic).
Uses include (generally gram positive causes of these symptoms); fin and tail rot (split, ragged and deteriorating fin and/or tail), Popeye (protruding eyes, may be cloudy or hazy), gill disease (swollen, discolored gills, gasping for air and a decrease in activity) and secondary infections.
Tetracycline Hydrochloride mode of action is as a protein synthesis inhibitor via an aminoacyl-tRNA binding mechanism to the 30S subunit. Mode of resistance is the loss of cell wall permeability.
Tetracycline becomes dangerous past its expiration date. While most prescription drugs lose potency SLOWLY after their expiration dates, tetracycline can become toxic over time.
This can be a useful antibiotic, especially when others fail, however Tetracycline is more useful in warm blooded animals (humans and Veterinary) than in fish.
Another note with Tetracycline Hydrochloride is that it is easily absorbed where calcium is present in larger quantities, which often renders this antibiotic useless in saltwater and high GH (hard water) freshwater aquariums.
DOSAGE: 250- 500 mg per 20 gallons of water. Every 48 hours (24 hours for severe issues) with a 25% water change before each treatment. This product will not work in water with a ph above 7.5- NOT FOR MARINE USE! (also not effective in freshwater aquariums with a pH above 7.6)
Tetracycline Hydrochloride is found in (Recommended place to purchase to support this free information):
*Best not used concurrently with other antibiotics or chemical treatments (including Malachite Green (See note), although use in a bath with Methylene Blue is OK.
USE: Minocycline hydrochloride, also known as Minocycline, is a member of the broad spectrum tetracycline antibiotics, and has a broader spectrum than the other members, especially as to gram negative bacteria where Minocyline has more activity (albeit still limited effectiveness when compared to other gram negative antibiotics).
Minocycline is also synthetic whereas Tetracycline Hydrochloride and Oxytetracyline are naturally occurring. It should also be noted that Minocycline maintains serum levels 2-4 times that of most other tetracyclines (150 mg giving 16 times the activity levels compared to 250 mg of Tetracycline Hydrochloride at 24-48 hours).
It has excellent anti-inflammatory properties which makes it a good choice for septicemia, although for Viral Septicemia there is no effective treatment, only prevention.
For more about Dropsy, please see this article:
Minocycline is also skin absorbed like Kanamycin (although not as well) which can increase effectiveness. It is also nontoxic to invertebrates but should not be used in Marine aquaria.
Minocycline (like other Tetracyclines) is easily absorbed by calcium, making this a POOR choice for saltwater or high GH freshwater aquariums (such as African Cichlids, livebearers), in these cases Kanamycin is the better choice.
The above point is often missed by well meaning aquarists (often in many forums that love to recommend Maracyn-2).
Another note about the dangers of Minocycline as with Tetracycline, is that Minocycline becomes dangerous past its expiration date, in other words expired Minocycline can become more toxic over time.
With these points in mind, generally the ONLY aquaria I recommend Minocycline in are Amazon River tanks such as Discus Aquariums.
DOSAGE: Maracyn-Two is the primary source for this anti-biotic, follow directions given by Mardel (manufacturer of Maracyn –2)
*Best not used concurrently with other antibiotics or chemical treatments, although use in a bath with Methylene Blue is OK
QUININE SUFATE (As well as Chloroquine & Quinine Hydrochloride):
Quinine Sulfate/Hydrochloride which is considered the first human anti malarial drug, works by causing a pH elevation in intracellular organelles of parasites, this is thought to disrupt the intracellular transport of membrane components and macromolecules, and phospholipase activity leading to cellular failure of these parasites.
Chloroquine was developed from Methylene Blue (also used starting in 1891 as an anti-malarial drug) & Quinine Sulfate in 1934. The formula of Chloroquine & Methylene Blue is also similar (MB: C16H18ClN3S / Chloroquine: C18H26ClN3).
As noted, Chloroquine or Chloroquine Phosphate is a related drug to Quinine Sulfate or Quinine Hydrochloride that is more effective from my experience (but also easily and fatally overdosed). When combined with Pyrimethamines as in the product "Marex", it can be very effective for treatment of Oodinium as well as other Ectoparasites and Flukes.
Chloroquine Phospate is a drug that degrades quickly in water and must be pure to be effective, with most aquatic sources are not 99% pure.
A better use of Chloroquine Phosphate is in a synergistic combination with Pyrimethamine, which Pyrimethamine is generally used to treat serious parasite infections (toxoplasmosis) of the body.
This combination found in AAP Marex works more quickly than chemical treatments such as copper since it immediately acts on the parasite, including in gill filaments, which copper and many other chemical treatments only act on free swimming stages of many Ectoparasites.
USE: Quinine Sulfate/Hydrochloride is useful for resistant strains of Ich (especially on scale less fish), as well as Protozoan caused sliminess of the skin and Rams disease (symptoms of whirling disease).
DOSAGE : 250 mg per 10 gallons of water. Once a day for 4-5 days. Do a 25% water change before each treatment. Quinine Hydrochloride is generally safer than Quinine Sulfate more effective when available.
Quinine/Chloroquine is found in (Recommended place to purchase to support this free information):
Doxycycline is a wide spectrum antibacterial synthetically derived from oxytetracycline that is generally superior in our aquatic environments.
USE: Oxytetracycline & Doxycycline will treat gram-positive (such as Streptococcus) and some gram-negative bacteria (such as some Vibrio species) found in aquarium/pond environments.
Both Oxytetracycline & Doxycycline can be used in a medicated fish food soak
DOSAGE: 250- 500 mg teaspoon per 20 gallons every 48 hours (24 hours for severe problems) with a 50% water change before each treatment. This antibiotic is best used mixed in with food, especially if your ph is above 8.0.
*Best not used concurrently with other antibiotics or chemical treatments, although use in a bath with Methylene Blue is OK.
Source for (Recommended place to purchase to support this free information):
USE: Bactericidal for some gram-positive and many gram-negative bacteria causing disease in fresh water and marine fish.
This synthetic antibacterial is effective for control of Flexibacter/Columnaris such as these symptoms: Fuzzy, thin, white coating on the body and fins.
It is best combined with Kanamycin for effective treatment of Columnaris pathogens, in fact the COMBINATION of Nitrofurazone and Kanamycin is often the only effective treatment for Columnaris.
Nitrofurazone is also often effective for Aeromonas such as these symptoms: fish have blisters forming on the skin that are full of a clear to yellowish fluid, these blisters may turn into large sores.
Nitrofurazone is particularly useful for control of minor topical skin infections of freshwater & marine fishes that have not become systemic. As well, Nitrofurazone is effective for surface skin infections of Streptococcus iniae which may appear as a milky peeling slime.
Serious adverse events related to nitrofurans are very rare. Acquired resistance of bacteria to nitrofurans during therapy has been rare and has not appeared on a significant scale in over 50 years of use.
Nitrofurazone is not Skin absorbed, so use of this Bactericidal for systemic infections is NOT recommended.
As well since Nitrofurazone is often better topically for Aeromonas while Kanamycin's skin absorbing properties combine well with Nitrofurazone for Columnaris.
Source for (Recommended place to purchase to support this free information):
DOSAGE: 250- 500 mg per 20 gallons. Treat every 48 hours (24 hours for severe problems) with a 50% water change before each treatment. Treat for 10 days.
Nitrofurazone is also found in AAP PolyGuard and Jungle Labs Binox
Another form for Nitrofurazone that is especially useful for infections in cooler water environments, goldfish & koi, and even plants (for a 1/2 hour bath/soak) is Nitrofura G (aka Nitrofuracin Green Powder).
A more useful combination treatment for un-diagnosable fish diseases and fish die-offs is the use of Furan 2 at full strength along with the Medicated Wonder Shell. The Medicated Wonder Shell has some Methylene Blue, but also has other wide spectrum ingredients for many external parasitic, some internal parasitic, fungal/Saprolegnia and some bacterial problems. As well the product adds essential mineral Cations that ALL fish need for osmoregulation and improved fish immunity.
Source for these products (Recommended place to purchase to support this free information):
*Do not use in the presence of live plants or many delicate invertebrates, including shrimps, some crabs, urchins, & more
USE: Neomycin (a Aminoglycoside) is a broad spectrum antibiotic that is effective for aerobic gram-positive, some gram-negative such as Aeromonas of the gut, and occasionally Mycobacterium tuberculosis (Mycobacterium marinum), which is neither Gram-positive nor Gram-negative due to high lipid content in its wall.
Effective for some Gram-negative bacteria- Open red sores or ulcerations, intestinal infections, fin and tail damage. As noted, Neomycin can be effective for wounds, ulcerations, or large sores, however I have found best results when used in combination with Triple Sulfa for such issues (used in a fish bath at double dose can also yield better results).
In severe cases where fins and tail are eaten away- treat with Kanamycin for this.
Aminoglycosides such as Neomycin are mostly ineffective against anaerobic bacteria, fungi, yeast, and viruses.
Neomycin is not absorbed by the intestinal tract and is effective in treatment of diseases thereof. But Neomycin can damage the kidneys as it is nephrotoxic when it enters the bloodstream, however since this drug is not readily absorbed in the intestinal tract it is useful for treatment of pathogens such as Aeromonas, particularly of the gut, that can lead to Dropsy or similar diseases.
More about: Dropsy
Neomycin works well in freshwater or saltwater aquariums.
For external use, Neomycin is more limited in use and should be used as you would the Human product; Neosporin.
DOSAGE: To prepare medicated fish food with flake, FD, or frozen fish food; Use One Measure (2-5 gallon "in tank" dose) of Neoplex per 15 minute fish food soaking for an average 60 gallon bio load aquarium (I use "just enough" water to mix fish food and Neomycin).
For in tank treatment; 250 mg per 10 gallons of water.
Further Reference: TB in Fish, Mycobacterium Tuberculosis
Neomycin is found in this product (Recommended place to purchase to support this free information):
*Do not use with fish suffering from inflammatory or ulcerative gastrointestinal disease
USE: Metronidazoles primary use is for the treatment of anaerobic gram positive bacteria including those that produce beta-lactamase. However, it is not effective against aerobic bacterium.
Due to Metronidazole effectiveness against anaerobic bacteria (by selectively blocking some of the cell functions of anaerobic bacteria) this drug along with Neomycin is a good choice for bloating of the digestive tract (common in goldfish). Metronidazole when combined with Neomycin sulfate in a medicated fish food slurry can be a very good full spectrum internal/gut infection treatment, treating both aerobic and anaerobic bacterium.
Further Reading: Aquarium Medications; Food Delivery of Medications
Metronidazole is also a good choice for many protozoan parasite infections, especially for Cryptocaryon in marine aquaria.
Metronidazole is also effective used in combination or by itself for internal parasites such as Nematodes or Trematodes. In marine aquarium infections is where Metronidazole really shines as it is very effective internally and since Marine fish are always drinking the water around them, medication is easily transported to the infected area. In Freshwater, treatment can be improved by soaking food as well and this is still an effective freshwater treatment as well.
Common aquatic uses for Metronidazole; Hole in the head disease (hexamita), chilodonella, plistophora (parasite disease usually seen in neons and cardinals that causes loss of color, darting, and eventually death.
Metronidazole can be combined with Nitrofurazone and Methylene Blue (1/2 dose for the Methylene blue) for an alternative treatment for anchor worms, especially for Trichlorfon sensitive fish.
DOSAGE: 250-500 mg per 20 gallons. Treat every 48 hours (24 hours for severe problems) with a 25% water change before each treatment. Treat for 10 days.
To prepare medicated fish food with flake, FD, or frozen fish food;
Metronidazole is often used in treating early stages or for prevention of Neon Tetra & FNT Disease.
*AAP General Cure
ABOUT/ USE: An easily absorbed antibiotic, it is used to treat many sensitive gram–negative and some gram–positive bacteria.
Kanamycin works especially well in salt water aquariums.
As noted a few times earlier in this article, Kanamycin works well combined concurrently with Nitrofurazone for flexibacter (Columnaris), which may includes these symptoms; fuzzy, thin, white "saddles" on the body and fins.
Also useful for Pseudomonas-Open red sores or ulcerations, fin and tail damage, fins and tail are eaten away, in severe cases, down to the body.
Kanamycin is one of the more effective broad spectrum antibiotics available with recent tests showing it to surpass the Tetracycline class antibiotics in cultures including Minocyline (found in Maracyn II), although Kanacyn has been also been shown in these studies to be even more effective when combined with other antibiotics such as Nitrofurazone or Tetracyclines for a “super” antibiotic effect.
I personally have found this to be one of the more effective antibiotics available (similar properties to Chloramphenicol, although still not as effective as Chloramphenicol which is no longer available in the aquarium trade).
As noted earlier, Kanamycin can be blended with other medications in particular Nitrofurazone to make a synergistic wide spectrum treatment.
Kanamycin can also be combined with Furan 2, although not quite as effective since these have different treatment schedules that do not allow for maximum synergistic effect and also separate treatment voids the negative affects of high pH upon Nitrofurazone that the use of AAP Spectrogram over comes.
DOSAGE: 500-750 mg per 20 gallons. Treat every 48 hours (24 hours for severe problems) with a 25% water change before each treatment. Treat 3 times or up to 10 days in severe cases (with water changes immediately before each treatment).
Kanamycin is found in (Recommended place to purchase to support this free information):
*While often one of the few aids to treating early onset Dropsy, care should be exercised since Kanamycin will also damage or destroy Kidneys if over used or if the kidneys are already severely compromised.
*Do not mix with ampicillin as these will reduce effectiveness of Kanamycin
Chloramphenicol has in vitro activity against most anaerobic bacteria (gram positive/negative), and aerobic gram-positive bacteria making this one of the more effective antibiotics I have ever used for fish due to its wide spectrum effectiveness, especially as per many aquatic bacterial pathogens (and even some parasites too).
Unfortunately the toxicity of Chloramphenicol, which has been linked to the development of aplastic anemia (a rare but potentially fatal condition) and dose-dependent leukopenia, has made this antibiotic impossible to find for most aquarists due to strict regulation, with Kanamycin Sulfate the closest substitute (although still not as useful in my experience)
ABOUT/ USE: Fin and tail rot, infections attributed to kidney disease (often not true kidney infections), some causes of pop eye, False Neon Tetra Disease/FTD, and certain causes of "Black Molly disease".
Erythromycin is most effective for gram-positive (the drug of choice for Streptococcus & Eye Infections in fish) and SOME gram negative bacteria and fungus appearing diseases, not what is generally considered true fungus).In fact there is sadly much misinformation about the use of Erythromycin for "True Fungus" which is incorrect as one Betta Forum diagnostics incorrectly recommended Erythromycin for Fungus which any check of most medical literature will show NO recommendations for such treatment. The use of Erythromycin for a true fungal infection will waste precious time and likely result in the death of your fish. If it is effective, the aquarium keeper likely was NOT dealing with a fungus
It is also noteworthy that not all Erythromycin is equal. Most is sold as Erythromycin Sulfate, which is less effective and even has a lower spectrum of treatment than the preferred but often hard to find Phosphate.
Erythromycin is considered primarily a gram positive treatment and should be used accordingly
Generally Erythromycin is not effective for most common aquatic diseases, especially in saltwater aquariums since it is primarily gram positive while the majority of aquatic infections are gram negative.
Another often effective use of Erythromycin is for eye infections, both pop eye and cloudy eyes (cataract like infections), however in both cases a medicated Methylene Blue/Salt bath should also be part of the treatment (if possible, as some large fish this is not possible).
I find that Erythromycin (often in the trade named product Maracyn) is one of the most improperly recommended aquatic medications available (based on feedback from clients and reading forums, especially Yahoo Answers).
Erythromycin works by inhibiting protein synthesis by binding to the 23S rRNA molecule (in the 50S sub-unit) of the bacterial ribosome blocking the exit of the growing peptide chain of sensitive microorganisms.
Gram-positive bacteria accumulate about 100 times more erythromycin than do gram-negative microorganisms. The non ionized from of the drug is considerably more permeable to cells, and this probably explains the increased antimicrobial activity that is observed in alkaline pH, which is why Erythromycin is more effective in pH over 7.2
PLEASE NOTE!! It is also well established among experienced fish keepers (as well as my own extensive use) that Erythromycin is VERY harsh on nitrifying bacteria (even though established as primarily gram negative), especially above 7.2 pH and should be used with care in aquariums, although in established aquariums the nitrifying bacteria will generally bounce back.
Having a "pre-seeded" (with aerobic nitrifying bacteria) sponge filter or other filter media in another healthy tank to move over to the Erythromycin treated aquarium is very helpful in quickly re-establishing/repairing your aquarium nitrogen cycle.
I would not recommend Erythromycin in new aquariums or Marine Aquariums due to activity that can harm bio filters.
Further Discussion: TheReefTank; erythromycin & nitrifying bacteria
Generally Erythromycin is best not combined with other medications, although I have combined with Kanamycin under careful observation of aquarium ammonia levels.
DOSAGE: 250- 500 mg per 20 gallons every 24 hours with a 25% water change before each treatment. Treat for 10 days.
Erythromycin is found in (Recommended place to purchase to support this free information):
*Do not use in new aquariums (under 8 weeks) where the nitrifying bacterial colonies are likely not well established
ISONIAZID 300 mg:
Isoniazid Can be combined with Kanamycin or Neomycin.
Unfortunately, Isoniazid has become very difficult to obtain since the premier aquarium medications company, "Aquatronics" went out of business due to the declining business climate in the aquarium industry.
An organic alternative is Usnea, which has shown very good lab results in treating the Mycobacterium tuberculosis.
Note: Aquatic tuberculosis can be very difficult to treat (in fact nearly impossible).
Further Reference about TB in Fish:
DOSAGE: 1 tablet per 20 gallons, every other day for 14- 30 days
PENICILLIN & AMPICILLIN;
USE: Belonging to the group of beta-lactam antibiotics, ampicillin is able to penetrate Gram-positive and some Gram-negative bacteria.
All medications, antimicrobials, antibiotics, chemotherapeutics work differently in differently in different organisms, even if the processes are similar. An example I often use is for Quinine Sulfate; this is a generally safe and effective treatment for fish, but not at all for invertebrates.
NALIDIXIC ACID (Naladin):
Nalidixic Acid is a quinolone, a family of broad-spectrum antibiotics.
For this application Naladixic Acid works best combined with Metronidazole or Gentian Violet. Although for this condition I prefer a Methylene Blue bath and Metronidazole in the aquarium (or possibly AAP Super Ich Plus or ParaGuard).
Naladixic Acid is also often a good product to use for symptoms of whirling disease or unexplained fish deaths, especially when the cause is unidentified, but fish keeping dying. Combining with AAP Super Ich Plusl can be helpful with unexplained fish death use.
Caution should be used with Nalidixic Acid in hard water aquariums as high amounts of calcium will interact with this antibiotic.
*Use of Naladixic Acid in aquariums with higher levels of magnesium, calcium, or iron can affect effectiveness. Discontinue Wonder Shell use and planted tank GH ferts during use for best results.
BLENDS/AAP Professional Treatments Medication Combinations
AAP Professional Treatments blends many antibiotics, anti-microbiral, & chemical treatments for a more synergistic and effective treatment
While many of medications can be blended, they do not have the full synergistic kick unless blended intentionally in ratios that also allow for optimum concurrent use. An example would be blending Nitrofurazone with Kanamycin Sulfate.
AAP Spectrogram is now being brought back as a much more convenient way to utilize the Nitrofurazone/Kanamycin Sulfate wide spectrum combination treatment, especially for difficult cases of Columnaris or Aeromonas.
AAP Discomed is the ultimate blended "feeding" antibiotic blend. This product blends ingredients that address a wide variety of internal parasitic issues, as well as osmoregulation & some internal bacterial issues/
For very serious combination bacterial/fungal/parasitic infections (such as Ichthyophonus or even virus infections such as “Angelfish aids”), especially in often difficult to treat Loach, Botia, Cory Catfish and similar fish.
If used EXACTLY as prescribed, these are some of the better fish treatment combinations I have every used and is especially good when fish are dying suddenly for causes that are not clear.
OPTION ONE;; AAP Spectrogram can be combined & AAP Super Ich Plus (or ParaGuard) OR Medicated Wonder Shell for a strong fungal, & bacterial infection treatment.
While this can be harsh on the aquarium system, it is generally safe for most fish and a healthy well established aquarium.
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