Treatment, Identification of: Aeromonas, Furunculosis, & Vibrio in Aquariums & Ponds
Also symptoms or manifestations of these bacterial pathogens such as Septicemia, Pop-Eye, Intestinal, swim bladder and occasionally Dropsy in Fresh or Saltwater.
By Carl Strohmeyer-PAMR 35+ years experience
Aeromonas and Vibrio (along with Aeromonas' cold water cousin Furunculosis) are anaerobic gram negative bacterium with similar manifestations such as infecting wounds, gastroenteritis, as well as being the primary bacterium cause of hemorrhagic septicemia. Other manifestations may include pop-eye and Dropsy.
Since Aeromonas salmonicida most often has its root causes in water conditions, successful treatment nearly always requires addressing these issues. In fact I have witnessed many an aquarium where the same treatment regimen was followed from one tank to another, where one tank would fail while the other was successful; the only difference was correcting these issues before and while treating (see the Prevention Section for more).
Please read further for more in depth descriptions and treatment/prevention methods for each.
Vibrio is a lactose-fermenting, anaerobic, gram-negative bacteria. It is slightly curved and rod shaped, and is an opportunistic pathogen, found in saltwater/marine or brackish environments. This organism causes wound infections, gastroenteritis, and is a common cause of “hemorrhagic septicemia” (see the picture below in the Aeromonas section for Septicemia) where the microorganism enters the blood stream, resulting in septic shock, rapidly followed by death in many cases (about 50% of infections).
Pimafix and a tea made Usnea Lichen are natural treatments that have shown some effectiveness for Vibrio, but is often a weak treatment at best so only mild cases should be treated this way.
One of the most common infections in freshwater fish is caused by the rod-shaped bacteria Aeromonas, which is also a gram negative, facultatively anaerobic, lactose-fermenting bacterium.
This bacterial pathogen is common in Goldfish, Ciclids and many other Tropical Fish. This bacterial infection can show itself in a wide variety of symptoms. Affected fish may have shallow or deep ulcers somewhere on the body, but may exhibit other signs such as exophthalmia (pop-eye), areas of bloody spots, and a distended abdomen. Infected fish with open sores appear to spread the disease to other fish, and sub clinical carriers may exist, shedding bacteria in their feces.
Aeromonas infections are probably the most common bacterial disease to infect Tropical Freshwater Fish.
These gut infections, which may or may not even include an actual Aeromonas infection may also mimic some internal parasitic infections. This determination may be difficult short of a necropsy (which means the dissection of a fish that died within a couple of hours).
It is also noteworthy that while water quality is the more common cause of Aeromonas infections, gut infections can happen in aquariums with otherwise healthy water conditions.
A few key points to prevent/treat these gut problems (please note if a full blown Aeromonas infections gets started, the treatments given further in this article may be needed):
Back to water quality as a determining factor:
Water quality, high amounts of organic decomposition, and low oxygen levels are major distinguishers between Aeromonas and the often confused with bacterial disease "Columnaris".
It should be also noted that since Aeromonas is facultatively anaerobic (aerobic respiration is advantageous, but not necessary), so improving oxygen levels and circulation is often important for prevention and recovery.
What is also noteworthy from my many years of experience with 1000s of clients over these years is that aquarium, bowls without any established bio filter have a VASTLY higher incidence of Aeromonas infections, whether internal or external or both.
Here is a source for a simple but effective aquarium/bowl bio filter:
Common Symptoms of Aeromonas are (expanded upon in further sections);
Aeromonas (along with Vibrio in brackish and marine) are common causes of hemorrhagic septicemia. Note; Septicemia is often incorrectly identified as a disease of its own and called "Red Pest", however it is not rather a symptom or condition.
Septicemia happens whereby the microorganism enters the blood stream, resulting in septic shock, rapidly followed by death in many cases.
Ulcers may be observed in conjunction with a hemorrhagic septicemia which can produce non-specific lesions and clinical signs of exophthalmos (Abnormal protrusion of the eyeball), ascites (An abnormal accumulation of serious fluid in the abdominal cavity), and visceral petechiation (Small red or purple spots on the body), and a hemorrhagic and swollen lower intestine and vent.
Unfortunately once septicemia is widespread within the fish in question, usually the prognosis is very poor regardless of that the aquarium keeper does both medicinally and improvement of water conditions.
When Septicemia is present, Tetracycline products including Minocycline (Maracyn 2) should NOT be used as these can exasperate the problem by lowering red blood cell count.
POP EYE:As noted earlier, Aeromonas (along with Pseudomonas Bacteria which is also gram negative but is aerobic) is one of the more common causes of bacterial “pop-eye” in fish.
A recent university study dealing with Trout found that removing stressors (including oxidative stress) and improving oxygen levels often cleared eye infections without medication. Although sometimes direct medication applications such as Silver Nitrate/Potassium Dichromate (1st choice), Merbromin (2nd choice), OR Potassium Permanganate (3rd choice) and hospital tank treatment with Erythromycin or a Kanamycin/Nitrofurazone is necessary.
Even though Pop-Eye is a symptom of more than one possible cause (such as Aeromonas), one thing that is common to this malady is fluid build up behind the eye.
Please see these articles for more about Dips and Baths:
*Aquarium Disease Prevention
See this article for more about Streptococcus as a cause of Eye Infections:
INTESTINAL BLOATING & SWIM BLADDER INFECTIONS (aka SBD):
Aeromonas can also be a factor in swim bladder or intestinal problems, especially when food is allowed to decompose on the bottom of the aquarium where fish (especially goldfish) may come along and consume it; also soaking dry foods in water prior to feeding cuts down on intestinal Aeromonas infections (as does healthy water parameters).
As noted earlier in the Aeromonas Overview Section (other considerations), gut or digestive issues may not even start with Aeromonas or even be caused by poor water conditions & poor fish osmoregulation, but can these conditions can provide fertile grounds for an Aeromonas infection to take hold.
With some cases of bloating (such as the picture to the right) the cause is most likely osmoregulation resulting in fluid buildup. Unfortunately, once it gets to this point, it is often not treatable, although a medicated fish bath with sodium chloride, Epsom salts, & Methylene Blue may help.
It is also noteworthy that swim bladder & bloating problems are a syndrome, NOT a disease per say as there are many causes or combinations there of including Aeromonas bacteria and feeding low fiber diets.
With Bettas, poor water conditions due to ammonia spikes and other water quality issues can be a cause of swim bladder Aeromonas infections. Since many bettas are not kept in filtered containers, I strongly recommend finding some way to either add a good bio filter (such as AAP Hydro Sponge #1) or adding products such as Matrix to the bowl bottom or better in a small flow through medicine bottle (AmmoChips and other similar products can be used, but these are not as effective long term for these ammonia spikes).
Generally for Swim Bladder infections simple fish baths described later in this article should be the first treatment step as well as withholding food for a couple days, and increasing mineral/electrolyte levels in the tank (this can be done with products such as Regular or Medicated Wonder Shells which are also especially helpful for fish such as Bettas not kept in filtered aquariums.
Further Reading: Fish Baths for treatment of swim bladder and bacterial issues
Product Resource: Regular or Medicated Wonder Shells
Another simple remedy for swim bladder or other bloating issues is a thawed and shelled frozen pea fed to the fish. While this is more for constipation, if constipation is at the root or even just a part of the problem, this can help as can feeding frozen, live, or even FD Brine Shrimp.
Reference: Fish Nutrition
Recommended Product Resources that support the hobby AND this FREE information:
When Aeromonas goes systemic (internal) it has been shown to be a major contributor to Dropsy (which is a kind of catch all diagnosis for bloating with distended scales usually caused by kidney and sometimes liver maladies).
Prevention is the key here;
Please see this more in depth article (from Aquarium Answers) about Dropsy: "Aquarium Answers; Dropsy in Fish"
Treatments of Aeromonas in tropical freshwater aquariums include:
Pimafix AND Melafix (combined) but only for VERY MILD infections, especially mild wound infections (Melafix by itself is rarely effective on Aeromonas though since it is gram positive).
Nitrofurazone for more serious infections, which SHOULD be combined with Kanamycin for an even stronger combination treatment is generally my recommended default staring place for in tank or hospital tank treatment.
Best to use an already combined product such as AAP Spectrogram being a more synergistic combination of Kanamycin/Nitrofurazone and is easier to use and pharmaceutical grade too.
Neomycin is an excellent antibiotic when mixed with food that delivers medications internally to infections (although this is primarily a gram positive antibiotic, it is anaerobic in activity and it should be combined with a gram negative antibiotic such as Kanamycin for better results).
An alternative for Aeromonas infections is Doxycycline, which is the best, most wide spectrum product from the Tetracycline family
Triple Sulfa is also a medication worth considering, especially in cases of Septicemia (caused by Aeromonas or other pathogens).
When Aeromonas is the primary cause of fin & tail rot, AAP Maracyn Plus is a synergistic combination of Sulfamethazine & Trimethoprim and can be an effective treatment. HOWEVER, do NOT use use if fish have large wounds or are suffering from septicemia as Trimethoprim can lower blood platelets and use can be fatal in fish already suffering from such issues.
Please see this article for more about fish baths:
This said, both being Tetracyclines, these can have many drawbacks for many aquarium applications (including being less effective with gram negative bacterium) and should only used in rare instances (please follow the previously noted link for further information).
Aquarium Salt or AAP Cichlid Salt can also be added at a rate of 1 tablespoon per 5 net gallons of water as an additional treatment to those above and the baths below (for livebearers, brackish, puffer, etc. a good marine salt is suggested). However sodium chloride rarely replaces these treatments, only compliments.
Resource for the BEST Marine Salt (also sold by the pound): Tropic Marin Ultra Premium Sea Salt
For ulcerations/sores (which are quite common with Aeromonas), I often recommend a direct swab with Merbromin (AAP Aquarium Wound Control).
I also recommend medicated baths of about 30 minutes using either Methylene Blue at double normal in tank strength using tank water for this bath, then disposing of the bath water after completion.Methylene Blue used in a bath is often a good choice for internal manifestations of this bacterial pathogen such as Swim Bladder, intestinal, Dropsy or Pop-Eye due to its effectiveness in tissue penetration.
In fact in Swim Bladder and intestinal Aeromonas infection, the MB Bath (along with possibly 1-2 teaspoons of salt and ¼ teaspoon of Epsom salt per gallon of bath water) followed by changes in water in the main aquarium, changing diet and/or withholding food for 2 days (dry foods should be soaked for 5 minutes prior to feeding), establishing a GH level of at least 100 ppm (for positive Calcium, Magnesium mineral ions) and 1 tablespoon of salt per 5 gallons may be all that is necessary for treatment.
If this does not remedy the problem then treatment with medications such as Kanamycin, Metronidazole, or Neomycin in a fish food soak. My preference for intestinal infections would be a combination of Metronidazole and Neomycin in this fish food soak (these can also be used in the bath, but are not as effective in reaching the source of the infection as fish food delivery).
If just one fish is infected, treating in a hospital tank that has an established bio filter often is best, but since Aeromonas often has its root causes in water parameters, these MUST be addressed regardless of where the fish is treated.
WATER PARAMETERS/AEROMONAS PREVENTION:
As noted earlier in the section dealing with Dropsy, water parameters, filtration and more is important for prevention AND ongoing treatment.
In Coldwater freshwater fish the similar pathogen is Aeromonas salmonicida also known as furunculosis.
In higher pH applications (8.0 + in particular), Triple Sulfa and Kanamycin are generally the better choice. And on some strains of Furunculosis, Tetracycline has shown occasional effectiveness.
Pimafix often combined with Melafix is an organic treatment shown to be effective for Aeromonas, especially in pond applications.
Outside reference for Furunculosis:
It is important to note that both Aeromonas and Vibrio pathogens are opportunistic bacteria that are more virulent in poor water conditions.
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