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TB in Fish, Mycobacterium Tuberculosis; Bettas & more
By Carl Strohmeyer-PAMR 40+ years experience
Fish Tuberculosis is generally caused by Mycobacterium marinum, a bacterium closely related to the human TB (Tuberculosis) bacteria, Mycobacterium tuberculosis, although incidents of Mycobacterium triplex have also been reported with Bettas.
Despite some internet claims, based on my many years of "house calls" and other professional aquarium maintenance work has shown Fish "TB" to be relatively uncommon with the exception of cases where the bacteria has been passed around and the fish' immune system has been compromised, this is especially the case with recently confirmed Mycobacterium triplex.
This seems to be more common among breeding and showing circles/clubs where water equipment cross contamination is common.
The above said, be careful about assuming your fish have Fish TB, unless all symptoms are present and treatment for more likely infections have failed.
However Bettas and Gouramis for reasons not 100% known seem to be more susceptible or have been placed in conditions where tuberculosis is more likely to overcome the fish' immune response.
Please read the "PREVENTION" section for more about TB in Bettas in particular
Treatment for Mycobacterium tuberculosis is often long and not always successful, as well low fish immunity due to poor aquarium parameters (including Redox Balance), along with fish age or even simple stress from tank mates can add to treatment difficulties or make treatment impossible (especially since Fish TB is difficult to treat anyway)
A myth I have seen written in a few "circles" (for some reason I have found this myth especially common on certain Betta Forums), is that Fish TB can also cause full blown human TB which is simply not true (only mild localized infections in healthy adults humans).
However it is still best to avoid fish to human transmission, especially if your immune system is compromised in any way.
Generally when the Mycobacterium marinum bacteria infects humans it is a dermatological issue as the bacterium usually enter the skin via small abrasions or cuts when you are performing aquarium maintenance.
The symptoms in humans are usually restricted to skin and soft tissue destruction in most instances of Mycobacterium marinum infection via small purple lesions that can gradually grow. It is noteworthy that in my decades of professional aquarium maintenance with literally 1000s of aquariums, I have only noted a couple of proven fish to human TB transmissions, so be careful of alarmist web sites.
Another myth about Fish TB, especially since it seems to have become the aquarium fish disease "De Jour" (disease of the day), is its transmission.
Based on emails, phone calls and discussions with my maintenance friends, you would think every fish that is sick now suddenly has this disease.
While it certainly seems to be more common and virulent as per confirmed cases, it is NOT commonly present in an aquarium (unlike Aeromonas, Columnaris, or Pseudomonas bacterium).
So in the case of fish that have been living in an aquarium for months and often years without any outside exposure to other fish, the facts are it is impossible for the fish to suddenly come down with a Mycobacterium infection!
Usually this false diagnosis with no history of possible exposure is simply the result of a simply weak or old fish showing symptoms that are often common to Fish Mycobacterium (TB).
What is also very noteworthy with a fish that may be showing symptoms common to Mycobacterium, if the fish dies within days of the first symptoms, it is VERY LIKELY that your fish did NOT have Mycobacterium as generally Mycobacterium kills slowly!!
Even with potential exposure, in my experience with confirmed cases of Mycobacterium, transmission usually ONLY happens in aquariums with old, genetically weak, injured, or with poor tank water parameters (which includes a poor aquarium Redox Balance).
In other words, under normal conditions this is not a highly contagious fish disease!
Then as per poor water conditions, genetically weak, poorly fed, etc. fish, it is more likely the fish have another bacterial infection and correcting these conditions is job one. Most common with Bettas in particular is lack of mineral Cations resulting in poor osmoregulation and increased oxidative stress (poor Redox balance)
If staining for identification, Mycobacteria stain bright pink against a blue background (as these bacterium are acid fast).
However, most aquarium fish keepers do not have the ability to grow cultures or make slides; so the symptoms of Fish TB are usually wasting away, lesions on the fish' body, loss of scales and/or coloration, and especially skeletal deformities such as curved spines.
The Betta fish in the picture above (please click to enlarge) displays classic symptoms of Fish TB in finage, skeletal deformity, and wasting to the point light can slightly penetrate her abdomen as seen in the light spot.
From Testing for "Fish TB"; AquariaCentral
The fish to the right is a largemouth bass showing clinical signs consistent with mycobacteriosis; note the ragged fins, sores, and general deterioration of the fish, differing from more common fish diseases such as Aeromonas and Columanaris.
Mycobacterium triplex can only be identified by 16S rDNA sequencing, so positive identification is difficult.
As with ANY fish disease, always start with getting your aquarium water parameters in order (as well as feeding), which in most my client house/office calls over the years with TB or copycat fish diseases this was a major issue.
Reference this article for more in depth help here:
A Healthy Aquarium, Fish Disease Prevention
Time of Treatment is VERY long and is generally administered for at least three months. Cure rate is well under 50%, but also do not believe those who state it cannot be cured as I have many times.
A hospital tank treatment is advised for fish TB since this generally is a very long treatment regimen and a three month treatment of ANY antibiotic can result in serious damage to your aquarium bio filter.
The three most proven antibiotic methods, which can and should be used in a combination of two of these drugs along with the other described alternative treatments:
*Isoniazid (from Aquarium Medications Part 2)
Sometimes a Sulfamethazine/Trimethoprim Combination can be effective too.
*Sulfamethazine/Trimethoprim Combination (sometimes effective)
Often a "cocktail" of these medications along with a fish bath (mentioned next) is needed for any hope of success, which can be very harsh on the aquarium environment. So unless the infection is systemic, a hospital tank might be best (adding a TRUE level one capable UV Sterilizer to your main tank is suggested to check spread, see later in the prevention section of this article.
A fifth consideration, albeit less field tested (it does show lab results though) is Usnea, which from my experience should only be administered in a "Fish Bath" form for 30 minutes. Methylene Blue should also be used in this bath, but no other antibiotics should be used in this bath with Usena.
These baths can be rotated; meaning one bath with Usena and Methylene Blue and the next bath with MB along with one or two of the other antibiotics, then back to the Usnea
Usnea is best as a used as a bath ALONG with an in tank treatment with one of the first three noted medications (or better hospital tank).
Further Information: Organic Fish Treatments; Usnea
A sixth consideration is Allicin, the active ingredient in RAW Garlic. Mycobacterium marinum) has been demonstrated to be effectively treated with Allicin, at least in vitro.
SeaChem Garlic Guard can be used in a fish food slurry preparation and mixed with both Neomycin and Kanamycin for improving the potential effectiveness of tuberculosis treatment.
See: Fish Nutrition; Garlic
Recommended Product Resource:
Garlic Guard; for Fish TB, Appetite Enhancer
A final consideration that might be helpful, in particular if the diagnosis is INCORRECT (which is common), is the use of Medicated Wonder Shells. These address many aspects of fish health, including problems that are simply symptoms of fish old age and not any disease in particular.
While a Medicated Wonder Shell is not a strong treatment for any particular disease, these are helpful as both follow up treatments and mild treatments that also address essential water parameters that might be out of balance (such as Redox).
Recommended Product Resource:
Medicated Wonder Shells
Back to Fish Baths; regardless of the medication or combination of medications used in tank, I suggest a Fish Bath with one of the first four before mentioned treatments (not garlic) at least once per day during this time period.
In fact in some cases the fish baths were all that was needed for success assuming these were carried out regularly.
Now for the bad news, from experience and others, once the fish became emaciated I had little to no success saving them.
Please Read/Reverence these Articles:
*Aquarium Medications; How Medications Work, and Which Ones to Use and Not to Use
*Fish Baths, How to Perform
Treatment of Mycobacterium triplex (not M. marinum) in human studies has shown it to be nearly impossible with only reduction of symptoms, not eradication of the bacterium.
These treatments used levofloxacin, ethambutol, and clarithromycin; all of which NOT available in fish medications.
You best bet with this rare strain (assuming your fish even has it), is to sadly euthanize and sterilize EVERYTHING, then start over.
How NOT to Treat:
The use of salt either in baths or in the aquarium will have absolutely no affect on Mycobacterium tuberculosis since this bacterium thrives equally well in salt or freshwater.
Temperature increases or decreases have little effect and in fact a temperature increase over 30°C. (as with Columnaris) often worsens a Mycobacterium tuberculosis infection.
Temperature decreases has shown some anecdotal slowing of the progression of Mycobacterium tuberculosis, but no cure.
There is not a 100% proven way to prevent Aquarium Fish Tuberculosis (as with most pathogens), however based on my own observations going back to 1977 (working at a Pet Store Fish department and then my aquarium maintenance company), I definitely noticed patterns.
Emails from customers and questions I see asked in forums and elsewhere have added to this same pattern.
Here are a few known factors:
- High organic loads, water quality characteristics common in intensive systems, and very crowded populations can all exacerbate the infection.
- Feeding feeder fish, fish remains, fresh worms and similar. Better if fish TB has been a problem a truly top notch prepared fish food such as Clay Neighbor's AAP Custom.
- One pattern is what I noted earlier and that is Bettas and Gouramis have a higher incidence of both suspected and proven cases of Mycobacterium marinum Tuberculosis infections.
I also noted that certain vendors (wholesale suppliers) would have a higher incidence of TB infected fish, so avoiding the purchase of fish from places that you have suspected TB on numerous occasions may also be helpful; this said, do NOT write off a retailer or vendor based on 1 or 2 suspicions of Fish TB, as it may have been another disease pathogen, as well frankly no vendor/retailer is perfect!.
Also be careful with Betta shows or similar, as I believe that this is both a major stressor AND infection point.
- As for procedure you can do to prevent Fish TB infections; there are many.
The most obvious is as stress free an aquatic environment as possible since stress due to many factors seems to be a major factor based on my work and research.
This includes stress from water conditions and tank mates.
Changing water regularly, maintaining a stable pH & KH, near 0 ammonia (NH3) and nitrites, a balanced Redox and ESSENTIAL aquarium positive mineral ions.
*Aquarium Chemistry; In Depth, from Beginner to Advanced
*Aquarium Redox for Fish Immunity, Health
The use of Aquarium UV Sterilization with a correctly applied UV Sterilizer performing at Level 1 Sterilization (this will NOT and CANNOT be achieved with the many low end UV Clarifiers such as the Green Killing Machine, AquaTop Hang On and similar water clarification ONLY devices flooding the market!).
The correct use of a UV Sterilizer can aid in Redox Balance and in the end also aid in fish immunity and is a MUST for an aquarium with a history of Fish TB to check the spread based on my extensive experience with Fish TB and true UV Sterilizer use.
MUST READ Reference:
Ultraviolet Sterilization, Facts & Information; Including Level 1 & 2
Recommended Product Sources:
Level 1 & 2 UV Sterilizers
Clay Neighbor's AAP Custom Super Premium Fish Food; Far Ahead of any other!
The use of SeaChem Garlic Guard or similar in fish food can also be used in an ongoing basis to improve fish health and prevent Fish Tuberculosis.
Back to Bettas in particular, a problem I have seen based on patterns that are almost 100% identical and that is many Betta Forums and Clubs will pass around the same methods of Betta keeping that can increase the likelihood of TB infections.
This includes constant chasing of pH, 100% water changes, keeping of Bettas in very small closed environments, lack of positive mineral ions essential to immune response, passing around fish (with constant exposure and stress), and limited gene pools due to interbreeding.
My suggestion is to keep your Betta in a system with a larger volume of water with small individual containers.
Within this system these practices can aid in TB prevention:
- Good bio filtration with quality sponge filters, or even better Fluidized Sand Bed filters, use of products such as SeaChem Purigen to further "clean" the water.
*AAP High Capacity Hydro Sponge Filters
*AAP Premium Fluidized Sand Bed Bio Filters
*SeaChem Purigen; Clears Water of Dangerous Toxins
- Maintenance of a stable pH & KH with as little of an effort as possible using products such as Alkaline Buffer, Acid Buffer, Driftwood, Pillow/Frog Moss, blended RO Water; IF NEEDED!
*SeaChem Alkaline Buffer
*Zoomed Frog (Pillow Moss) for Natural Water Softening
- Constant drip of ESSENTIAL mineral ion replenishing products such as SeaChem Replenish, or BETTER and more simply with AAP Original Wonder Shells This is one of the major causes of symptoms of Fish TB as the lack there of results in poor osmoregulation and higher oxidative stress.
As well to not be overly concerned with GH.
Further Reference: Aquarium Chemistry, GH
Product Resource: AAP Wonder Shells, Mineral Supplement, Unique Version
- Do NOT pass your fish around in environments out of your control and attempt to bring new fish into your breeding operations from sources you are not 100% sure of.
- Utilize a GOOD Level 1 UV Sterilizer such as the TMC Vecton. Do not fool yourself into complacency with one of the many UV Sterilizers sold for under $50 via Amazon or similar discounters, as there is not a one that can perform level one Sterilization (most do not have HO UV lamps and are missing pre-filters that are required)!!.
UV Sterilization; Water Flow for Level 1
Buying Aquarium Products via Amazon (& Chewy, eBay)
Product Resource: TMC Vecton Premium High Dwell Time Aquarium, Ultra Violet Sterilizer
If you are breeding Bettas, keeping the Bettas within isolation boxes/containers with a much larger 'cubical based centralized system' is a practical way to utilize a good UV Sterilizer, as well as maintain much better water quality.
The picture below displays aquarium cubicals that I highly suggest for anyone serious about breeding bettas so as to be able to maintain more stable water quality and also utilize UV Sterilization!
These cubicals can be placed in larger aquarium and can also be blacked out to prevent interaction between Bettas.
However the cubicals do allow for interaction of "smell". My suggestion for this is to keep certain Bettas at different points in their breeding cycle together in the same aquarium system (in other words multiple systems
See also the articles below in the references/resources dealing with Aquarium Disease Prevention for more help in Fish TB prevention
*Mycobacterial Infections of Fish
*Fish Diseases; Univ. of Florida
*Aquarium Disease Prevention; Proven Steps
*Mycobacterium triplex Pulmonary Disease in Immunocompetent Host
By Carl Strohmeyer
Other Suggested Resources, Products
AQUARIUM AND POND INFORMATION;
Well researched and up to date aquarium and pond answers, help, and links
*Columnaris in Aquarium Fish (also Fungus)
This is easily the most in depth and regularly updated on the subject of Columnaris and Fish Fungus to be found ANYWHERE on the Internet!
*The Aquarium Nitrogen Cycle
The most up to date article on the subject of the Aquarium Nitrogen Cycle, based on both research and 35+ years of professional experience with 1000s of client aquariums!
This article covers many aspects of Aquarium & Pond UV Sterilization from how, why, facts, myths, and maintenance including the importance of changing UV Bulbs regularly.
UV Bulbs; Page 1
As noted above, changing these PREMIUM bulbs/lamps every 6-12 months is essential for a properly functioning UV Sterilizer
*Aquarium Silicone Sealant; USDA 100% Fish Safe
100% Fish Safe, USDA & Agricultre Canada approved, the same CANNOT be said for Hardware Store brands!
Excellent for building aquarium systems of multi-tier fish housing.
Aquarium Lighting; Basic, Reef, Planted
The above referenced article is easily the most in depth and regularly updated on the subject of Aquarium Lighting to be found ANYWHERE on the Internet!
Atison's Spa Clear; Indian Almond Leaf Conditioner
Clear Betta Spa contains wild almond leaf extract to simulate the natural environment of the native soft water fish.
Other natural botanicals, including Yucca extract, help control ammonia, reduce stress and maintain cleaner water.
FISH AS PETS
Fish as Pets with articles & commentary of Interest to the Aquarium Hobby
*Planaria & Detritus Worms in Aquarium; Which is Correct?