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A few weeks back I posted about my dwarf neon rainbow (female) who seemed to be wasting away. To update...I've treated with Jungle Parasite clear (twice in 48 hours, with 25% water change as directed). My water parameters are very good. No other fish seem affected. She's eating well (only tubifex worms and frozen bloodworms...won't eat flake food). She's still pretty active, although the male doesn't seem to like her...chases her away whenever he sees her. Any other ideas what might be wrong with her??? Should I remove her to a quarantine tank???

Dwarf neons are like a lot of other rainbows in that they can sometimes require very high oxygenation, moreso than a lot of other fish, the symptoms you describe are classic for the fish needing higher oxygenation, particularly if they currently have or have suffered from mycobacterial infections, the symptoms often leading to gill damage. Certain medications and some nitrate reducing tank additives like tetrabalance for example will temporarily lower oxygen levels from the result of their denitrifying chemicals working, and I have personally witnessed that can be all it takes to start a rainbowfish from showing these symptoms. The primary cause of non feeding in rainbowfish is usually low oxygenation, most species are very resistant to worms and other internal parasites.Dont forget a lot of rainbows, even the ones sometimes described as lake fish are in fact often river fish , and the same species can be adapted to two radically different ways of life.Some can take low oxygenation, but most cant.She may be eating (although often they will stop in low oxygen) but without the oxygen she needs she will not be metabolising the nutrition from her food, and she will be passing it largely undigested. She will also be immuno-suppressed

If I may give you an example of one of my more successful smaller rainbow tanks (a 4 footer)- I have 2 9inch bubble curtains and an eheim spray bar shortened to disturb the water surface over nearly a half of the length of the tank. Without the use of venturi nozzles there really is no such thing as overkill on oxygen in a rainbowfish tank.

Mycobacterium spreads aggressively but it may be months until fish finally succumb to the disease.A quarantine in a tank with high oxygenation and treatments of metronidazole is advised. Remember ALL species of rainbowfish die from mycobacterium infections so treat any rainbows that you have.

Rainbowfish rarely act territorially to the degree of fatality but they will persecute sick fish.You might need to seperate her for the duration of her illness.

Neons will also be sensitive to nitrate higher than 40 ppm so check into that too.



Last edited by longhairedgit at 06-Oct-2005 22:40

Interesting! And co-incidental. My tank is a 35 gallon. I have not used any water treatments other than adding a little baking soda to my water when I do water changes (good pure well water, no chlorine). Up to now, filter was a large (HOB) Whisper power filter plus an additional airstone in the tank. Water turbulance appeared more than sufficient to me, and there are several live plants in the tank, but with no actual way to measure the oxygen, how can I know???? The co-incidental part is that just two days ago my filter started to leak from a crack in the housing, so I purchased a new one. Wanting to get a bigger tank in the not too distant future, I went for a much larger capacity filter, a penquin 350. There is no flow adjustment on the unit and after installing it on the tank, I actully wondered if its TOO strong for my current tank due to the turbulence it seems to be making. The fish don't seem to mind however, so I'll leave it for now.

In the meantime, I'll remove the sick fish to my 10 gallon quarantine tank, repair and install the large Whisper on that tank, add an airstone and do another dose with more Junge Parasite Clear? One more up-date, when I checked the tank last night, I noticed one other fish (not sure what it is...a very old had-him-for-years pale blue tetra), had some sort of rupture in its belly...an actual hole and some contents spilling out. Had not noticed any signs of illness in this fish previously. I euthanized him. Could this be related??

With the tetra it sounds like a very advanced case of amoebic or protozoan infection, Aeromonas hydrophilia ,or as is more likely a Tetrahymena corlissi protozoan infection- the effects of which can cause necrosis of the stomach and gastro intestinal walls, the acidity within the stomach and the spreading culture can effectively blow holes in fish.Older specimens are especially susceptible and it is a common cause of death in fish where the advancing age can reduce the effectiveness of their immune system. Septacaemia can also do this but it usually takes a wound to get it started.

This does not really mean that the disease would spread to rainbowfish unless the tank was overcrowded , and hopefully the blanket medication you have used will have killed much of it off, but it does illustrate that water conditions in your tank may also be suitable for Mycobacterium (tuberculosis) to be present, as I have highlighted on previous occasions the only really effective treatment for this is metronidazole in the concentrations only a vet can legally provide. Most broad spectrum treatments that are commercially available will not touch it.Both aeromanas and mycobacterium infections can be extremely persistant, often needing repeated treatments and neccisitating the complete cleaning and sterilisation of all aquarium equipment before they can be eliminated. Mycobacterium should also be taken seriously as its possible that you could become infected personally , and not only become quite seriously ill, but act as a vector for the spread of the disease to other aquaria or reinfect treated fish.

If I could have more details about the fish you keep in the tank, the temps , ph, water quality etc I might be able to be a bit more accurate as regards a course of action.


As to the issue of currents- rainbowfish usually appreciate a bit of current, but a sick one may become exhausted,particularly if its not digesting food properly, so you might want to think about perhaps diffusing some of the current towards the surface and return it to normal after the fish is better.


Sometimes the change in equipment or breakdowns no matter how slight can cause things to get out of hand, a cracked filter could lose flow or pressure and changing tanks is rarely a stressless procedure. Its sounds like youre fairly conscientious with your fish and it may just be bad luck, made worse by the fact that we keep species from different regions of the world in the same water.

I wish better luck for you. Best wishes to your lil rainbow.



Last edited by longhairedgit at 08-Oct-2005 09:17

Thanks so much for the input. Was away for our Thanksgiving, so as of yet, nothing has changed. She's still hanging in there...eating well, fozen bloodworms only....I think perhaps she's lost a little of that concave look???? Anyhow, as to your request for the parameters....

35 gallon community tank, re-established about 6 months ago (i.e. old tank/decor, but changed gravel and restocked with almost all new fish), with stable parameters:

Nitrate: 40 ppm
Nitrate: 0
Total Hardness: slightly higher than 120 ppm
Total Alkalinity: 180 ppm
PH: 7.6
Temp 76
25% water changes every 2 weeks, with addition of ~1tsp baking soda added to new water
New penquin 350 filter installed ~ a week ago
Food: Flake food, dried tubifex worms, frozen bloodworms

8 Harlequin Rasboras
3 Black Tetra
3 Dwarf Neon Rainbows* 1m, 2f
6 Cory
1 remaining "blue" tetra...very old

Is there any point to quanantining her at this point??? I'm thinking it may be more stressful to her and if it is some sort of communicable thing, would they not all be infected by now anyway???

As a side note...I've worked in several vet clinics over the past 15 years as a veterinary technician...no vet I've ever worked for had any clue as to treating aquarium fish and the proper dosages of medications...althoug I supposed they probably do have the resources to research the needed info. I'm helping out at a rabies clinic this afternoon...I'll ask the vet. In the meantime, any and all advice still welcome.

While doing a bit of reading I recently discovered that combined infections of aeromonas hydrophilia and mycobacterium are in fact one of the most common causes of dropsy outside of the carp family ,( which actually get it frequently as a result of another specific infection)the report I read was a collation from pathology reports investigating deaths from dropsy, and its clear that the actual swelling is caused as a result of renal failure. Failure of the kidney is caused by contributing diseases and so the visible dropsy we see ( swollen bodies, eyes and raised pinecone like scales) is actually the result of kidney failure. So its entirely possible that dropsy in a small tetra might not be immediately visible,as kidney failure will not neccesarily swell the fish and may cause internal organs and tissues to rot, thus blowing a hole in the fish in the stomach or gastrointestinal regions.Presumably a lot of these deaths from kidney failure without the classic sign of dropsy will be put under the "mystery deaths" section, although their causes are the same.

Mycobacterium primarily invades fish kept at lower than normal temperatures, as the compromised immune system in fish at those low temps allows it to invade. This would explain why many people have fish that suffer dropsy as a result of water changes, low temps and environmental changes or equipment failure.

Aeromonas hydrophilia proliferates in dirty conditions and will be quite commonly present in a number of aquaria, but unless combined with mycobacterium doesnt commonly cause dropsy, although it can cause tissue rot.

So basically unless you have koi, or related fish , dropsy will be caused by

1) kidney failure due to the feeding of fatty foods and overfeeding.Its possible that fish who get dropsy by this cause are the most likely to recover, as a period of fasting, often enforced by the symptoms of dropsy itself may cause the fish not to eat.This fasting will in a few cases cause the reabsorbtion of some of the fats that were blocking the kidneys and liver in the first place, thus alleviating the problem.In some cases it may not be overfeeding so much as offering a diet that is simply too rich for a given animal.

2)Tannic toxicity in water, as this can be a heavy load for a fish to process thus affecting the kidney. People with dying plants, seriously tannin loaded bogwood or people who go ape with the blackwater extract should take note- especially when exposing fish from different regions to blackwater conditions they normally wouldnt be expected to tolerate.

3) a combination of disease or any single disease that causes degeneration of the kidney( as already mentioned).

4) parasites like flukes, that again will attack the kidney.

I mention all this because since I believe that both diseases may be present in your tank, and your fish have recently undergone a period of change and thusly have suffered some immune system affecting stress, so I would recommend treating the tank with metronidazole asap , and then continue with an antibiotic treatment after that. Should flukes be the causative agent you can also treat the water with salt.This way you might be able to treat symptoms of each disease and eliminate the dropsy risk.

Its also better to treat sooner than later as most common antibiotics actually put demands on the liver and kidneys and work with them to produce antibacterial compounds in the body.If you treat too late, the antibiotic could well kill a fish with kidney damage as it will not be able to cope with the increased demands on its renal system.You have to treat before the renal system becomes too impaired.

One thing to bear in mind with bicarb- it is extremely volatile and causes water quality changes quickly-something most fish will NOT appreciate, id be tempted to go for another solution. Other than that your water perameters seem fine. You might consider raising the temperature gradually and temporarily to about 79 degrees for a few days , as this will accelerate the immune systems of your fish.

This all explains how dropsy can attack some fish and not others, and often transmission rates are very low. Transmission rates in dropsy are only high when you have the two causative diseases present in the tank, or the tissue from the dead fish is eaten by other fish, thusly transmitting the disease most effectively.

When you realise "dropsy" is actually just a symptom of KIDNEY DAMAGE and NOT a disease in its own right,it all becomes clear. Kidneys dont regenerate well and no wonder so few fish recover, even when the causative diseases are discovered and treated. In fact it might be useful if the aquatic community at large dropped use of the term dropsy and referred to it as what it is- kidney or even liver damage , the term dropsy is hugely misleading.


Since treating your aquarium under these circumstances is good practice anyway, theres no need to remove your rainbow for treatment. Should it die you should dispose of the body immediately.



Last edited by longhairedgit at 13-Oct-2005 23:54

Last edited by longhairedgit at 14-Oct-2005 00:03

oh yeah, and penguin 350's come with activated carbon as standard, so unless you have changed this, your meds will not be effective. All carbon should be removed until all med courses have been completed. If the filter hasnt been running for long it might not be stabilised yet, even though it may be cycled within 21 days, sometimes keeping stable perameters can take months.


Last edited by longhairedgit at 14-Oct-2005 00:12

Well, I have twice withing a 48 hour period treated with "Jungle Parasite Clear" which contains praziquantel, difluorobenzamide, acriflavine AND metronidazole....(and yes, did remove carbon from filter). Are you suggesting treating again...or with pure metronidazole? Working with a vet, I have access to just about any med, but as I said, I did ask and none of the vets I know have any clue as to dosages for fish...and not an aquarium keeper in the bunch!!! I can raise the temp and add salt...but how much??? As to her condition today, I think I can honestly say she's looking a wee bit fatter. Perhaps the treatment did work and its just taking a bit of time for her to recover???? So, should I re-treat?

As for the baking soda....prior to adding my fish, I experimented with my water for at least a month. I determined that I HAD to add the baking soda because my well water is low alkalinity. Just adding untreated well water DID cause a change in my water parameters...which I knew would not be appreciated by the future tenants. Adding a small quantity of bs to the "change water" seems KEEP my water stable. I continued to test for several months after adding the fish, before and after water changes, to make sure their was no fluctuation at all in my parameters. Thought this was good thing...I should mess with it???

repeated treatment with metranidazole is a good idea , as flaggellate protozoa can be very persistant, and no , if the water qualities are stable now theres no need to mess with it. I thought you were regularly adding bicarb to tank, but if you add it to the water before the change and let it sit for a few hours the activity of the bicarb will reduce and impact your tank less.

Last edited by longhairedgit at 16-Oct-2005 01:02