BLOAT - Photos & Treatment


Staff member
MFK Member
Apr 27, 2005
To treat Bloat, the plan of attack is:
Metronidazole and water changes, water changes, water changes!!

1. Remove carbon/resins from filter.
2. Perform a 30-50% water change (reduces free-floating bacteria/protozoan population)
3. Add salt (teaspoon to a tablespoon per gallon) to aid the fish's osmotic regulation processes. Use Rift Lake Salt for African species (Calcium chloride vs sodium chloride in table/sea salt).
4. Treat with 200mg/20gallons of Metronidazole (Flagyl)
5. Leave for 3 days and do not feed.
6. After 3 days, perform another large water change.
7. Replace the salt.
8. Add full dosage of Metronidazole.
9. Wait another 3 days. During this phase, the bloat should be decreasing in appearance. In large fish, the water may take on an ammonia odor from the high volume of urea the fish should now be producing due to reducing the bloat and recovering renal activity.
10. 3rd day, another water change. Also, replace the salt and redose the metronidazole (full dose). If the fish looks to be well on the road to recovery you can offer a small feeding each day.
11. Another water change on the 3rd day. No meds but, I'd recommend the salt. You should be clear now.

This is the treatment I use on my africans, puffers, and my lungfishes/polypteridae. Knock on wood that it's worked every single time.

An old school method of treating bloat is with the use of epsom salt at the rate of 2 tablespoons per 10 gallons of tank volume. This method has been successful but, takes longer to treat than by using Metronidazole.

Note in the pics the abdominal distention caused by the bacteria and in a severe case, such as this, the scales are pushed away from the body.

Tokis-Phoenix adds: (For full freshwater (aka sweetwater))

There are many things that can cause bloating, constipation and dropsy being the main two.


The problem with treating this disease is that there are a number of "potential" causes: bacterial infection, parasites, cancerous tumors, virus', internal fungal infections or sudden temperature drop of more than 3 degrees.

If the cause is bacterial, the swelling typically comes on pretty rapidly. If swelling is gradual then one or more of the other potential causes are more likely. Unfortunately, treatment is most often useless at this point due to the advanced state of the disease process. When the illness, whatever the cause, has progressed far enough to cause internal swelling, the concomitant internal damage is usually too extensive to be repairable.

The latest research has shown that if the disease cause is bacterial and if the disease process is caught early enough, treatment with Romet B, a broad spectrum antibacterial, *may* be effective when used concurrent with an increase in water temperature to 84-86ºF for 2 weeks minimum.

BE CERTAIN to maintain HIGH OXYGEN LEVELS during such treatment since at these temperatures, water holds significantly less oxygen at these higher water temperatures. One of the suspected bacterial precursors to the disease process -- Aeromonas, is killed at these temperatures.

Concurrently add 1/8 teaspoon of EPSOM SALT -- per 5 gallons of water . Feeding foods soaked in ERYTHROMYCIN will kill the second suspected bacteria, Mycobacterium. In rare cases popeye has been found to be caused by Edwardsiella etarda. This is found *only* in fish that have been bred in outdoor ponds -- the functional bacteria in this case is carried by frogs. While fair to good results in treatment have been found by feeding Romet B., even better results have been found using injectable chloramphenicol or amakacin. This is best done by your veterinarian.

If parasites are a known cause, treat for them first for 3 days increasing the temperature to 86ºF as fast as possible.

EPSOM SALT may help reduce the internal pressure caused by the swelling. Extremely good aeration is necessary here due to the use of such high temperatures.

NEVER USE SALT (sodium chloride, a.k.a. aquarium salt) for treatment of dropsy. This will KILL your fish in a very short time. The affected fish are already having a difficult time getting rid of salts due to kidney dysfunction. This causes the blown up appearance and concurrent scale standing. The osmotic imbalance caused by addition of sodium to your tank water will make this condition far worse.

EPSOM SALT on the other hand, does not pass through the walls of the gut or gills and will extract water OUT of the surrounding tissue into the gut where it *may* be excreted.





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Fire Eel
MFK Member
Sep 13, 2005
Great info! So is "bloat" considered to be the same thing as "dropsy"? Looks similar from the looks of the flared scales.


Feeder Fish
MFK Member
Aug 15, 2006
loach43;584931; said:
Great info! So is "bloat" considered to be the same thing as "dropsy"? Looks similar from the looks of the flared scales.
wondering the same thing


MFK Member
Nov 14, 2005
Mobile, AL
Dropsy is a catch-all term for any bloating, regardless of cause, which leads to the scales standing out from the body.
Dropsy is not a actual disease/infestation in it's own right.

We've seen a rise in cases of 'bloat' at O'fish in the last couple of years, some of which seemed unresponsive/untreatable, autopsies performed by some keepers revealed internal growths/tumors.
But thankfully for the most part if caught early and the cause is treatable then survival rates have been better than 50/50.

I've indentified some of the primary reasons for bloat and a suggested treatment(s) in a small article I use for canned replies to the initial posting of threads dealing with this problem...
ChileRelleno said:
First the usual gamut of questions...
Tank size
Water parameters, NH3 NO2 NO3 PH, temp (need actual test results)
Established tank
New tank-mates/decor
Prior/recent history of illness disease
Current illness/disease symptoms/duration
Size/age of fish

This type of abdominal swelling is usually associated with constipation, internal infection, internal parasites, egg-bound or tumor/growth.
The first three usually are treatable, the latter not so much to not at all.

Constipation: Peas, pea with grain of Epsom salt within and Epsom salt bath/dips.

Internal infection: Either bacterial/viral, improve water quality, medicate water/food with wide spectrum antibiotics.

Internal parasite(s): Antiparasitical medication such as Clout and medicated foods.

Egg-bound: Attempt to strip the eggs (dangerous if inexperienced) or a shot of oxtocin from a vet.

Tumor/growth: :(


Fire Eel
MFK Member
Sep 13, 2005
Great info, thank you!:)


Feeder Fish
MFK Member
Sep 8, 2006
Davie, FL
What do you do if you have plants in the tank?


Feeder Fish
MFK Member
Apr 28, 2007
im about to pull out all the stops.
metronidazole, peas, and epsom salt....

Spot is worth it...