Aquarium Medications and Treatments, Antibiotics, antimicrobials

Aquarium Medications Part 2 | Antibiotic & Antimicrobial Treatments

Information about these Treatments:
(1) Sulfas
(2) Trimethoprim
(3) Tetracycline
(4) Minocycline (Maracyn 2)
(5) Oxytetracycline/Doxycycline
(6) Nirtrofurazone (& Nitrofura G)
(7) AAP Medication Combinations
(8) Quinine Sulfate/Hydrochloride, Chloroquine
(9) Neomycin
(10) Kanamycin
(11) Chloramphenicol
(12) Metronidazole
(13) Isoniazid
(14) Erythromycin (Maracyn)
(15) Penicillin/Ampicillin
(16) Naladixic Acid
(17) Blend Suggestions

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AAP MeWe Page

By Carl Strohmeyer-PAMR 40+ years experience
Updated 12/14/21

TRIPLE SULFA (Sulfamerazine, Sulfamethazine, Sulfathiazole) & Other Sulfa Based Medications:

Aquarium Triple SulfaSulfas are considered all anti-bacterials (antimicrobials).
These drugs are bacteriostatic, meaning they inhibit the growth of the bacteria but do not kill them.
Sulfas are generally most effective against aerobic gram-negative organisms, and occasionally effective against anaerobic gram negative bacteria, but are not reliable against aerobic gram-positive bacterium such as Streptococcus
More on: Streptococcus Eye Infection

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.
Animal cells are unable to synthesize folic acid and it must be provided in the diet. For this reason sulfa drugs are not toxic to animal cells.

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.
For aquatic use Sulfas are often maligned by many aquarists as not effective or out of date, yet in reality Sulfathiazole often will work where other antibiotics fail and sometimes with less side effects as well (this is not to say Sulfas do not have side effects as they are somewhat toxic, producing blood abnormalities and kidney damage when indiscriminately used).
Sulfas also do not tend to be as sensitive to poor use (meaning not following the full treatment regimen).

USE: A relatively broad spectrum antibacterial medication; for fin and tail rot, ulcerations, 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).
Sulfathiazole is very effective for basic Fin Rot infections with Pseudomonas as the bacterial pathogen. It is also useful for damaged fins caused by fin nipping.

Sulfas are still one of the better anti-microbials for wounds or large sores/ulcerations (Nitrofurazone and Neomycin are other potential choices or possible combinations). Generally a good pharmaceutical grade Nitrofurazone product such as AAP Yellow Powder is my first choice this use (note the popular product Furan 2 is NOT pharmaceutical grade), but Sulfas are a good 2nd choice that should be considered should Nitrofuarzone fails.
Use in combination with Neomycin for stubborn sores, in particular lower pH aquariums/ponds is also a consideration.

Sulfathiazole 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.
Further information: Fish baths, Dips, Swabs

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).
In fact when fish are otherwise healthy but for an injury or a few mild to moderate symptoms (such as redness), Triple Sulfa (or Super Sulfa) were often the go to treatment of choice with my aquarium maintenance clients. I generally reserved stronger treatments such as the AAP Yellow Powder/Kanamycin combination for later or full blown infections (which were more common with "fish doctor" calls, not my regular clients).

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.
As well Triple Sulfa has minimal impact on nitrifying bio filters when used correctly

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):
*AAP Sulfaplex
*Aquarium Pharmaceuticals; Triple Sulfa at AAP
*AAP PolyGuard
*AAP Maracyn Plus (contains Sulfamethazine and Trimethoprim) (Maracyn Plus is currently out of production)


*Best not used concurrently with other antibiotics/antimicrobials, although use with chemical dyes such as malachite green is safe and even advised.
*Do not use with copper based medications

If you have found this web site helpful (or the sister site Aquarium and Pond Answers), PLEASE consider a donation or purchase to help with the 1000s of hours of research and regular updates that go into these articles:


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.
In fact when combined with some Sulfa based medications, it produced a synergism or addition in 85% (similar to how Kanamycin and Nitrofurazone produce a synergism that treats Columnaris and Aeromonas that when treated alone, often results in failure).

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.
Especially useful for fin and tail rot.


*Can be very harsh to nitrifying bacteria in an aquarium, do not over dose and use only in well established aquariums.
*Can cause Thrombocytopenia (lowering of blood platelets), so this is a poor choice if fish have large wounds or are suffering from septicemia. A better choice then would be a pure Sulfa product or other medication combination.

Trimethoprim is found in (Recommended place to purchase to support this free information):
*AAP Maracyn Plus- contains Sulfamethazine and Trimethoprim (manufactured by Fritz/Mardel)

Combined Activity of Sulfamethoxazole, Trimethoprim,


API TetracyclineUSE: Tetracycline is the name of a large class of antibiotics produced by Streptomyces bacteria.
These include Tetracycline Hydrochloride (to be discussed here) and several others which, although closely related, often yield very different results (although side effects may be very similar).
With this in mind it is important to not confuse these very similar but often very different in results antibiotics. Unfortunately this is done all too often, especially for the treatment of Columnaris (Flexibacter).
Minocyline which can be effective (not my first choice for Columnaris though) is often confused with Tetracycline Hydrochloride.

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.
It interferes with the production of proteins that the bacteria need to multiply and divide (bacteriostatic). However many bacterial pathogens have developed resistance to Tetracycline Hydrochloride.

Tetracycline Hydrochloride is generally more effective for aerobic bacteria (which Columnaris is only aerobic however Aeromonas and many other pathogens can be anaerobic).
It should also be noted as to Columnaris that although it is aerobic, it is also gram negative, whereas Tetracycline Hydrochloride is less effective for gram negative bacterium.
It is noteworthy that a member of the tetracycline family; Minocycline hydrochloride is more effective for gram negative bacteria than Tetracycline Hydrochloride.

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.
Note, Tetracycline can lower red blood cell count and cause anemia, because of this I would not use with injured fish, as this is the last thing you want to do with a bleeding fish.

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.
I have often found the side effects to outweigh the benefits in aquarium use (such as anemia and interfering with nitrifying bacteria, often producing a “brown foam” on the surface of the aquarium), especially for marine aquariums.
For this reason (destruction of nitrifying bacteria) I strongly recommend against the combined use of Tetracycline AND Erythromycin (the side effects of these two antibiotics combined will generally negate any benefits obtained when used in combination).

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):
AAP Pro Series Tetracycline (manufactured by API)

Disease References:
*Columnaris (Flexibacter)
*Streptococcus in Fish, Eye Infections


*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.
*Do NOT use with fish suffering from ammonia/nitrite poisoning, acute damage from exposure to high heat, or with fish with low red blood cell count (anemia) such as suffering from an acute gill infestation of Velvet, Ich, Flukes or similar parasites that attacks the gills and thus renders a fish anemic
*Less effective in water with high calcium content
*Do not use with any iron oxide containing products
NOTE: Not recommended in combination with Malachite Green based on the fact Malachite Green is generally used for external parasites that can lower red blood cell count and that MG is more effective & safe at higher calcium levels while Tetracycline is the opposite.


Maracyn 2, MinocyclineUSE: 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.
Minocycline is also effective for some causes of fin/tail rot and OCCASIONALLY pop eye and is sometimes suggested for dropsy.
However as for Dropsy I strongly recommend against this as this antibiotic can cause severe kidney damage, which is the last thing you want with a possible Dropsy case.
However Minocycline (Maracyn 2) is not generally a good first choice for fish with sores; Nitrofurazone, Sulfa Products, and Neomycin are better choices for sores/wounds (especially the product AAP Nitrofuracin Green; Synergistic Nitrofurazone, Sulfathiazole Sodium, & Methylene Blue Full Spectrum Treatment).

For more about Dropsy, please see this article:
Betta with Dropsy

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 or BETTER, combined with "AAP Yellow Powder".
Product Resource: AAP Yellow Powder, Nitrofurazone

The above point is often missed by well meaning aquarists (often in many forums that love to recommend Maracyn-2).
The reason is that although Maracyn–Two (Minocycline) is a good product/medication when used in the right conditions for the right problem (of which it is relatively wide spectrum), the problem is that most aquariums I have either encountered or have been sent the water parameters for (emailed, etc.) have too high of a mineral level (GH over 200) for Minocycline to be truly effective.
In fact there in lies the problem in that often these same minerals that render Maracyn Two less effective, can IMPROVE the fish’ natural ability to fight disease (via better osmoregulation & Redox).
See more: Do Fish Drink, Osmorgulation

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
*Do not use with any iron oxide containing products
*While not as much a problem from my experience as with other Tetracycline products, Minocycline is still not a good first choice for use with fish suffering from ammonia/nitrite poisoning or with fish with low red blood cell count (anemia) such as suffering from an acute gill infestation of Velvet, Flukes or similar parasites that attacks the gills and thus renders a fish anemic

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).
It has also been well known for years that chloroquine has anti viral capabilities, in part it is believed by being an inhibitor allowing allowing zinc ions to permeate the viral cell wall. As well, chloroquine interferes with the metabolic communication between the bodies immune system cells. If the cells cannot effectively communicate with each other, then excessive immune response may be reduced.
Where this relates to fish is besides being a very effective treatment for some single cell parasites, I have observed some added effectiveness with inflamed gills, in particular when caused by Oodinium & Flukes.

PLEASE NOTE that while Chloroquine MAY have shown promise as a treatment for the Covid-19 Virus, likely due to known anti-viral capabilities, NO PERSON should take a fish medication to self treat especially taking 10 times the normal human dose as happened in Arizona. PLEASE seek a doctors advice! (it is also NOT used as a Fish/Aquarium Cleaner)

Covid-19 Coronavirus Treatment
VIDEO: Covid-19 Coronavirus Treatment 2020 | Aquarium Medications | Hydroxychloroquine & Azithromycin

*Hydroxychloroquine and azithromycin as a treatment of COVID-19
*Breakthrough: Chloroquine phosphate has shown apparent efficacy in treatment of COVID-19 associated pneumonia in clinical studies

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.
With this in mind be mindful of the discount aquarium product seller placebo product "New Life Spectrum's Ick Shield Pellets", even assuming properly soaked with pharmaceutical grade 99% pure Chloroquine Phosphate (which is doubtful), this product simply cannot work because Chloroquine Phosphate has only been proven to successfully target the free swimming stage of EXTERNAL parasites. Which is why you must dose the powder in a hospital tank. There is no proof it is effective on trophonts feeding on the fish. Even if food soaking were somehow effective on preventing trophonts from attaching, you'd have to be sure each & every one of your fish ate it for 72 consecutive days.
Bottom line, AVOID this product.

New Life Spectrum ick shield, Snake oil?
Fish Nutrition; Facts

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 with few side effects other than appetite surpression.
The product "AAP Marex" contains this combination.

Marex 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.
This Chloroquine Phosphate/Pyrimethamine combination is the fastest acting treatment I have EVER used for Oodinium & Brooklynella, although I have often found a follow up treatment with Copper or keeping the main aquarium without fish for 4 weeks will improve long term results.
This combination found in Marex has been proven in 100s of cases I've used during my professional aquarium maintenance years and is recognized by many in the hobby and industry as as close to a miracle cure you can get (at least for initial treatment with copper being good follow up treatment)

This combination of Chloroquine Phosphate/Pyrimethamine is also an excellent treatment for gill flukes in freshwater and can generally be safely combined with Praziquantel for severe cases.

Malachite Green & Quinine Hydrochloride for treatment of fish Ich, IckUSE: 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).
Also useful for resistant strains of Hexamita when combined with Metronidazole.
When Quinine Hydrochloride is combined with Malachite Green, this is one of the most effective and proven Ich and similar single cell ectoparasite treatments available! AAP Super Ich Plus is one such product that combines both and is the Ich treatment of choice for difficult cases of Ich (although for sensitive fish such as Cory Cats & Loaches this product/combination should be used at half dose and combined with Triple Sulfa).

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):
*AAP Super Ich Plus (Malachite Green & Quinine Hydrochloride)
*AAP Greenex (Marine version of Super Ich Plus)
*AAP Marex
*AAP PolyGuard (as quinacrine)


Aquarium Doxycycline, API Fin & Body CureOxytetracycline is a naturally occurring Tetracycline that is more broad spectrum than Tetracycline Hydrochloride (but not as broad spectrum as Minocycline, especially as to gram negative bacteria).

Doxycycline is a wide spectrum antibacterial synthetically derived from oxytetracycline that is generally superior in our aquatic environments.
Doxycycline also has been shown to have delayed anti-malarial activity, which is a similar pathogen to Oodinium & Ich found in our aquarium pond fish. However this is not a "best product" for this use in our aquarium fish

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.
Maladies include; Body Slime & Cloudy Eyes (its best use), Marine ulcer disease, cold water disease, bacterial hemorrhagic septicemia (Symptoms: Red streaks in body and fins), or redness in the body. Also open sores or loss of scales and mouth fungus.

Both Oxytetracycline & Doxycycline can be used in a medicated fish food soak
Reference: Aquarium Medications Part 1; Fish Food Delivery

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.
*Do not use with fish suffering from ammonia/nitrite poisoning, acute damage from exposure to high heat, or with fish with low red blood cell count (anemia) such as suffering from an acute gill infestation of Velvet, Flukes or similar parasites that attacks the gills and thus renders a fish anemic
*As with all Tetracycline products, less effective in higher calcium environments (although Doxycycline has a lower affinity for calcium binding than other Tetracyclines).
*Do not use with any iron oxide containing products

Source for (Recommended place to purchase to support this free information):
AAP Fin & Body Cure (manufactured by API)


USE: Bactericidal for some gram-positive and many gram-negative bacteria causing disease in fresh water and marine fish.
Nitrofurazone inhibits several bacterial enzymes, especially those involved in the aerobic and anaerobic degradation of glucose and pyruvate.
Often a good choice for fish wounds or large sores, especially in aquariums with a pH of 7.2 or lower along with a slightly lower GH. In fact pharmaceutical grade AAP Furacyn is generally my fist choice for ulcerations/sores (note Furan 2 is NOT pharmaceutical grade).
Triple Sulfa is often the better choice for high pH water or use in a combination with Neomycin or Kanamycin.

Nitrofurazone is also very effective for many coldwater fish infections and combines well with Malachite Green products to prevent secondary infections (especially in outbreaks of Ich).
Also Nitrofurazone can be combined with Dylox (AAP Dyacide) in treatment of ectoparasites to prevent secondary infection and in fact improve results.
As well Nitrofurazone in the form of "AAP Yellow Powder" can be used with AAP Medicated Wonder Shells to improve effectiveness and make the combination more wide spectrum (Furan 2 is not advised as much due to the need to treat daily).

This synthetic antibacterial (Nitrofurazone) is effective for control of Flexibacter/Columnaris such as these symptoms: Fuzzy, thin, white coating on the body and fins.
However it is best combined with Kanamycin for effective treatment of Columnaris pathogens, in fact the COMBINATION of Nitrofurazone and Kanamycin (when used concurrently) is often the only effective treatment along with removal of stressors 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.
As well Nitrofurazone is often effective for the related Vibrio and similar bacterial species.

Further Reference Information:
*Columnaris (Flexibacter) in Fish
*Aeromonas, Vibrio, Furunculosis in Fish

AAP Yellow Powder superior to other NitrofurazoneNitrofurazone 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.
Effective as well against marine ulcer disease and some protozoan infestations. For this reason, Nitrofurazone is a good next step treatment for wounds and other topical infections when first step treatments such as Pimafix or Melafix fail.
Nitrofurazone is also useful in treating Furunculosis often found in Koi, especially when combined with Methylene Blue (monitor ammonia levels when using with Methylene Blue).

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.
Do not use in the presence of invertebrates.
Nitrofurazone is more effective at lower pH levels, which means use for marine fish is best in baths, NOT the display aquarium!

Nitrofurazone is not Skin absorbed, so use of this Bactericidal for systemic infections is NOT recommended.
When Kanamycin and Nitrofurazone are combined and treated 100% concurrently, these medications form a synergistic combination that is not totally understood, but what is known is that often leaving one or the other out of the equation or not using both at full strength often results in failure in treatments of stubborn/advanced bacterial infections such as Columnaris.

As well since Nitrofurazone is often better topically for Aeromonas while Kanamycin's skin absorbing properties combine well with Nitrofurazone for Columnaris.
Since these bacterial infections are often hard to differentiate by the average aquarist, this can be a good combination when unsure.
Further Reference: Nitrofural, Nitrofurazone; Skin Absorbing

Source for (Recommended place to purchase to support this free information):
*AAP Yellow Powder; Premium Nitrofurazone Superior to other Nitrofurazone
*AAP Nitrofuracin Green; Synergistic Nitrofurazone, Sulfathiazole Sodium, & Methylene Blue- Full Spectrum Treatment
*AAP Nitrofurazone; Furan 2 (manufactured by API)

DOSAGE: 200- 500 mg per 20 gallons (varies due to product quality). Treat AAP Furacyn every 48 hours (24 with Furan 2 problems) with a 20-40% water change before each treatment. Treat for 8-10 days.

Nitrofurazone is also found in AAP PolyGuard and Jungle Labs Binox

AAP Nitrofuracin Green, Synergistic Nitrofurazone, Sulfathiazole Sodium, & Methylene Blue Full Spectrum TreatmentAnother 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 AAP Nitrofuracin Green.
This product is simply a combination of Nitrofurazone, Sulfa, & Methylene Blue.

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.
So when the Medicated Wonder Shell is combined with Furan 2 which has more anti-bacterial potential, you get a good wide spectrum treatment that along with correcting any water parameters or other issues can help when other remedies fail.

Source for these products (Recommended place to purchase to support this free information):
*AAP MethyBlu Premium Concentrated Methylene Blue (recommended)
*Methylene Blue from AAP
*Medicated Wonder Shells from AAP


*Do not use in the presence of live plants or many delicate invertebrates, including shrimps, some crabs, urchins, & more
*Not best used in saltwater display aquarium, better in hospital tank or bath with no carbonate based decor (corals, live rock, etc.)


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.
Neomycin is poorly absorbed internally. The lack of absorption from the gastrointestinal tract is the basis of the main use of Neomycin.

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.
As well, Neomycin can be PART of a treatment for mycobacterium tuberculosis (symptoms, weight loss, a distended abdomen, loss of appetite, fin erosion, unusual coloration, spinal deformities, and listless behavior).

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.
Neomycin is very effective when used in feeding due to the fact that this antibiotic does not get absorbed. This is my preferred way to treat with this antibiotic.

Aquarium Antibiotic Medications, Bio BandageFor external use, Neomycin is more limited in use and should be used as you would the Human product; Neosporin.
That use would be for minor cuts, injuries, etc., not for major bacterial infections, especially since most major external fish infections are gram negative infections that Neomycin is not effective for. External use would be also similar to recommended use of Melafix.

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).
After soak, pour entire contents into aquarium.

For in tank treatment; 250 mg per 10 gallons of water.
Treat every 24 hours with a 25% water change before each treatment. Treat for 10 days. For tuberculosis, use for up to 30 days (Can be and should be combined with other treatments such as Isoniazid for Fish TB).

Further Reference: TB in Fish, Mycobacterium Tuberculosis

Neomycin is found in this product (Recommended place to purchase to support this free information):
*AAP Neoplex- Neomycin (manufactured by SeaChem)


*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.
As well Metronidazole is effective for some protozoa (especially internal flagellates).

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.
Metronidazole selectively blocks some of the cell functions in anaerobic bacteria, resulting in their demise.

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.
It it is also noteworthy that Metronidazole is generally safe for most invertebrates, in particular shrimp and snails.

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.
(Please read “Neon Tetra Disease” in the reference section), salt water ich, bloat.

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.
Metronidazole is unique in some of its effectiveness and is excellent to combine with other treatments especially when affecting a cure is difficult (such as many internal parasites).
Probably the Aquarium Industries top fish remedy manufacturer, Aquatronics (that unfortunately went out of business), used Metronidazole in many of its multi antibiotic remedies as it very useful in combination.

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;
Use One Measure (2-5 gallon "in tank" dose) of Metronidazole 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).
After soak, pour entire contents into aquarium.

Metronidazole is often used in treating early stages or for prevention of Neon Tetra & FNT Disease.
Neon Tetra & FNT Disease

Metronidazole is found in (Recommended place to purchase to support this free information):
*AAP Metronidazole
*AAP General Cure


ABOUT/ USE: An easily absorbed antibiotic, it is used to treat many sensitive gram–negative and some gram–positive bacteria.
Kanamycin is a water-soluble aminoglycoside antibiotic that is derived from the bacterium Streptomyces kanamyceticus and has a very low adsorption rate in the intestine of animals including fish.
Aminoglycosides work by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth.
Aminoglycosides such as Kanamycin are useful in infections involving aerobic gram-negative bacteria such as Columnaris (especially when combined with Nitrofurazone).

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 very effective in high pH applications, especially Vibrio, making it useful for brackish and marine treatments. Kanamycin is easily absorbed skin absorbed, making it an excellent choice for systemic infections.

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.
Kanamycin can also be used for aquatic Tuberculosis (Mycobacterium marinum), although Isoniazid is often the drug of choice, both can be used together as Isoniazid seems to affect certain active TB bacterium whereas Kanamycin has often different TB activity effectiveness (Kanamycin can also be combined with Neomycin for difficult cases of Mycobacterium marinum.

I personally have found Kanamycin to be one of the more effective antibiotics available for some common fish fin bacterial issues & more (similar properties to Chloramphenicol).
HOWEVER Kanamycin is still not as effective as Chloramphenicol which it replaced in the fish keeping industry years ago (Chloramphenicol is no longer available in the aquarium trade).
This is the unfortunate part of the popular use of Kanamycin, in particular under the trade name "Kanaplex" as its predecessor Chloramphenicol was more wide spectrum, and more effective for diseases such as Columnaris. Kanamycin often by itself is not enough, so many will mistakenly purchase Kanamycin (Kanaplex) for their Bettas in particular and the treatment will often fail without the synergistic combination of Nitrofurazone or for other issues, combined with Metronidazole.

Kanamyacin may be effective for symptoms of whirling disease (not actual whirling disease), suspected kidney disease and dropsy. Kanamycin tends to be absorbed quickly by the kidneys which makes it effective for treatment of Kidney infection, but also lends itself to the destruction of the kidneys with over use.
Kanamycin sulfate appears to prevent bacteria from making their cell walls, so the cells die.

Premium NitrofurazoneAs noted earlier, Kanamycin can be blended with other medications in particular pharmaceutical grade Nitrofurazone to make a synergistic wide spectrum treatment.
When it comes to treating Columnaris in freshwater aquariums, when using AAP's recommended synergistic blend, is to also combine with the topical treatment of AAP Wound Control/Merbromin or Methylene Blue as well as fixing stressors that often make Columnaris more virulent, one can have a powerful treatment for this often lethal disease.

Kanamycin can also be purchased separately and combined with Nitrofurazone such as in the only pharmaceutical grade product "AAP Yellow Powder" (as well as the much less effective non pharmaceutical grade Furan 2).
If combined with Furan 2, it is not quite as effective since these have different treatment schedules due to the fact Furan 2 is not very pure & requires daily treating unlike Kanaplex or AAP Yellow Powder.
This does not allow for maximum synergistic effect nor for the negative affects of high pH upon Nitrofurazone that the use of the combination of AAP Yellow Powder and Kanaplex over comes.

Kanamycin is found in (Recommended place to purchase to support this free information):
*AAP Kanaplex (manufactured by SeaChem) For Nitrofurazone: *AAP Yellow Powder

Further 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.
Be careful with mixing Kanamycin & Neomycin (& Sulfa anti-microbials too) in the same treatment mix as this can further increase affects upon kidneys (use separately and even then with care in desperate situations such as Dropsy).
Further Reference: Dropsy in Fish

*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.

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Aquarium TreatmentsFor Aquarium/Pond treatment products to help with many aquatic diseases and conditioners, aquarium test kits, & more.

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Erythromycin, API ProABOUT/ USE: SOME cases of 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.

As well some websites and social media such as an unfortunately popular YouTube channel recommends Erythromycin as a first choice for fish fin rot, even though most causes of Fin rot are gram negative.
It is noteworthy that Maracyn and API Erythromycin are both the less effective and less wide spectrum Erythromycin Sulfate versus the more wide spectrum Erythromycin Phosphate (sold under AAP Myacin). Even with Erythromycin Phosphate, it is still not the antibiotic or antimicrobrial of choice for fish fin rot.

AAP Myacin, SUPERIOR Erythromycin PhosphateAs I mentioned earlier, 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.
Currently the only available product with Erythromycin Phosphate is AAP Myacin.

Further References:
Streptococcus, Eye Infections
Fungus; Saprolegnia in Fish
Neon Tetra Disease, FNT, Sporozoan

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.
This is not to say Erythromycin is a useless treatment for aquarium use, as it is still useful for some diseases especially some of the more difficult gram positive infections such as Streptococcus, some cases fin rot and even some causes of Neon Tetra Disease (not all as this is more a symptom of several possible causes rather than an actual disease).

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).
Direct application of Silver Nitrate or Potassium Permanganate may be necessary for severe cloudy eyes (cataract like eye infections).
When used for many eye infections (especially when only one or a small percentage of fish are effected), use of Erythromycin at double dose in a medicated fish bath is often an effective and definitely safe method of use.
Further Reference: Medicated Fish Baths, How to perform

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).
Although I have used this antibiotic with success, it is rarely a medication that I will go to first other than for specific diseases/conditions since it is limited in its aquatic effectiveness and is hard on nitrifying bacteria.
This is a medication worth trying when all else has failed or even in combination with antibiotics such as Kanamycin, but as a first choice Erythromycin should be very limited other than the before mentioned infections (such as Streptococcus & serious gram positive eye infections).

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.
Animals including fish do not have 50 S ribosomal subunits, but have ribosomes composed of 40 S and 60 S subunits.
Certain resistant microorganisms with mutational changes in components of this sub-unit of the ribosome fail to bind the drug. The association between erythromycin and the ribosome is reversible and takes place only when the 50 S sub-unit is free from tRNA molecules bearing nascent peptide chains.

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.
When used with faculative bacterial support products such as SeaChem Stability, this lowers the risk of dangerous ammonia spike issues.

Further Reference:
The Krib; Erythromycin vs Blue-Green Algae - a short article

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.
Use of a bare hospital tank with a seeded sponge filter is another idea when practical (not for aquarium wide infections).
Product Resource: SeaChem Stability

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
From the above discussion:
"I don't know who told you that the erythromycin wouldn't hurt the nitrifying bacteria, but let me put this in perspective.
It is very common practice to treat patients prophylactically with a form of erythromycin that is not easily absorbed (so that most of it stays in the gut) the day prior to gut surgery, as it is a type of surgery that is at risk for peritoneal (abdominal connective tissue) infection from the contents of the gut. Normally the dose is 1 gms at 1, 2 and 5pm the day prior to surgery, and the average volume of distribution for most patients at this dose is about 10 to 15 liters (how much apparent volume to account for the concentration of a drug in plasma) If we assume that it is 16 liters, and that there are approximately 4 liter in a gal, then we have 250mg of erythromycin in a gallon of body fluids, but this is the level that is intended to kill as close to 100% of the gut's flora as possible in the short dosing time that we treat the patient.
Even at low doses in the aquarium it will reduce the numbers of nitrifying bacteria, and has little discrimination in which bacteria it kills (the mechanism is that erythromycin binds to certain subunits of the 50S level of bacterial ribosomes, thereby preventing essential protein systhesis in the ribosomes). It's minimun inhibitory concentration (MIC) is as low as 0.003 mcg/ml for some spp of 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):
*AAP Myacin (SUPERIOR Erythromycin Phosphate) (this product is a much better choice over the lessor Erythromycin Sulfate found in API Erythromycin or Mardel Maracyn)
*AAP Pro Erythromycin (manufactured by API) or Maracyn by Mardel.


*Do not use in new aquariums (under 8 weeks) where the nitrifying bacterial colonies are likely not well established
*Do not mix with other primarily gram positive medications such as any Tetracycline
*Do not mix with Metronidazole as it can increase metronidazole activity, espeically in intestinal tract to dangerous levels
*Do not use if fish have Dropsy


Isoniazid for aquarium fish by AquatronicsABOUT/USE: Treatment for tuberculosis.
Symptoms include: the fish have been sick for several months, the fish is lethargic, anorexic, has fin or scale loss and a sunken stomach.

Isoniazid Can be combined with Kanamycin or Neomycin.
As noted, Isoniazid is used alone or can be used with other drugs to treat tuberculosis (TB) and to prevent it in fish that have had contact with tuberculosis bacteria.
It eliminates ONLY ACTIVE (growing) bacteria.
Since the bacteria may exist in a resting (nongrowing) state for long periods, therapy with isoniazid (and other antituberculosis drugs) MUST be continued for a long time (usually 6-12 months) often making TB treatments in aquariums impractical due to costs, time, and damage to the aquatic environment (I strongly recommend using a quarantine tank).

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.
Neomycin is an alternative for Mycobacterium tuberculosis, as well Kanamycin is considered a second line drug for Mycobacterium tuberculosis (not a first line since many strains of Mycobacterium tuberculosis are resistant to Kanamycin).

An organic alternative is Usnea, which has shown very good lab results in treating the Mycobacterium tuberculosis.
For more about Usnea, please see this Aquarium Answers article:

Note: Aquatic tuberculosis can be very difficult to treat (in fact nearly impossible).
Also note that this is caused by a very similar bacterium in human TB, but is not the same, and the only danger to humans is to an open wound exposed to the bacterium, which then only causes a localized rash.

Further Reference about TB in Fish:
TB in Fish, Mycobacterium Tuberculosis

DOSAGE: 1 tablet per 20 gallons, every other day for 14- 30 days


USE: Belonging to the group of beta-lactam antibiotics, ampicillin is able to penetrate Gram-positive and some Gram-negative bacteria.
Even though this a commonly used antibiotic family in humans and other warm blooded animals, this is a family of antibiotics that has shown to be GENERALLY USELESS in fish (especially Penicillin).
About the only effectiveness comes in the treatment of some fungal-like eye infections.

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.
The same goes for both Penicillin and Ampicillin, while these are often useful for humans, their use for fish is VERY LIMITED AT BEST, and should basically never be used in an aquarium.


Nalidixic Acid is a quinolone, a family of broad-spectrum antibiotics.
Nalidixic Acid (also known as Naladixic Acid and Naladin) is effective against many gram negative and some positive bacteria.
In humans it was, as the antibiotic is no longer used for humans, used for urinary tract infections.
Naladixic Acid is similar in its effectiveness to Septra (AKA Trimethoprin).

In aquariums it has been shown to be occasionally effective for swelling caused by fluids in the internal cavity of the fish that is often diagnosed as Dropsy.
It has also shown effectiveness in treating sporozoans (Pleistophora hyphessobryconis) sometimes referred to as neon tetra disease.

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.

Product Resources:
*AAP Naladixic Acid (Naladin)
*AAP Super Ich Plus
*AAP ParaGuard (manufactured by SeaChem)
*AAP Medicated Wonder Shells
*AAP MethyBlu (premium Methylene Blue)

BLENDS/AAP Professional Treatments Medication Combinations

AAP Professional Treatments blends many antibiotics, anti-microbiral, & chemical treatments for a more synergistic and effective treatment
AAP Professional Treatments

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.
While using separate medications such as Furan 2 & Kanaplex can certainly be effective, blending these in optimal rations and using 100% concurrently is impossible out of the package when used as directed, which is why products such as AAP Spectrogram is the better choice.
As well many medications that were once the mainstay of aquarium keeping professionals ceased to exist but are now being brought back, such as Naladixic Acid, Wound Control/Merbromin, and Eye Fungex.


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/
Resource: AAP Discomed

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.
This combination PLUS AAP/SeaChem ParaGuard OR better, a Medicated Wonder Shell can often be the “kick” needed for a cure, see below.
The Medicated Wonder Shell provides the biggest kick when added to AAP Yellow Powder, especially if Redox Balance is off with an aquarium that may have already been over medicated resulting in oxidative stress.
I often call this and the combinations below my "everything but the kitchen sink" treatments!

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;; Nitrofurazone (AAP Yellow Powder) can be combined & AAP/SeaChem ParaGuard OR Medicated Wonder Shell for a strong fungal, & bacterial infection treatment.
OPTION TWO;;Nitrofurazone (AAP Yellow Powder) can be combined with Metronidazole for a bacterial infection & moderate parasite & fungal treatment.
OPTION THREE;; use Nitrofurazone (AAP Yellow Powder), AAP/SeaChem ParaGuard, & Metronidazole (AAP/SeaChem Metroplex)for an excellent parasitic, fungal, & moderate 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.

Further Product References:
*AAP Medicated Wonder Shell
*AAP Yellow Powder(Nitrofurazone)
*AAP/SeaChem ParaGuard
*AAP Metronidazole (Metroplex, manufactured by SeaChem)
*AAP/SeaChem Sulfaplex (Sulfathiazole)

Information Reference:
Ichthyophonus, Aquarium Answers
Angel Fish Virus, Aquarium Answers
A Healthy Aquarium, Disease Prevention


Further reading/references:

*Treatment of Tuberculosis

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