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Bacterial Infection or Parasite?


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  • pH 7.2
  • Nitrates 15
  • Nitrite 0
  • Ammonia 0
  • KH/Buffer ?
  • Water Temperature 74

2 weeks ago I bought a few zebras and neons (different tanks in the store) and a few days later they had all died.  There was a brief ammonia spike to .25 and my nitrates were around 30-40 but the ammonia went away within a few days and I did a water change to rid the most of the nitrate.  Shortly after whatever it was spread to 4 other zebras that I had in the tank.  The first ones had fins that were frayed, a couple got popeye, and some had bloated bellys/red tints after they died.  Shortly after it spread to a few corys.  One also got a case of popeye and another ended up laying vertical on a leaf before dying.  So far it's taken out 7 zebras and 2 corys.  My neons are yet to die from this and it's hard to tell if I've lost any shrimp but most of them still look good.  Currently, most of the fish in the tank are opening/closing their mouths rapidly but they're not hanging out at the surface gasping for air.  The tank is also heavily planted with CO2 and uses a power filter that should provide enough surface agitation.  


I started treating with Maracyn 2 but that didn't do the trick and I'm now using paracleanse.  I'll let that sit for a week before water changing and trying something else.  Any idea what this could possibly be?  The fin rot and everything else made me think bacteria but now I've thought of the possibility of gill flukes due to the heavy breathing and some corys rubbing against eachother.  The rubbing isn't super apparent with other fish though so I'm not sure.  For all I know it could be a parasite that somehow got a secondary bacteria infection causing the popeye.  The lastest photos of the danios look like they have some extra mucus near the gills but it's hard to tell.  Sorry for the rough photos but it's hard to get clear ones with how fast these guys move when they see me trying to take them.  I can try to get better quality ones if it helps.


Edited by sfgiants13
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Possibly colunmaris.

From wikipedia: "An [columnaris] infection will usually first manifest in fish by causing frayed and ragged fins. This is followed by the appearance of ulcerations on the skin, and subsequent epidermal loss, identifiable as white or cloudy, fungus-like patches – particularly on the gill filaments. Mucus often also accumulates on the gills, head and dorsal regions. Gills will change colour, either becoming light or dark brown, and may also manifest necrosis. Fish will breathe rapidly and laboriously as a sign of gill damage. Anorexia and lethargy are common, as are mortalities, especially in young fish."





You can find people on the internet recommending every type of antibiotic for columnaris, from erythromycin to kanamycin/metronidazole/nitrofurizone combo. I don't have first hand experiencing in what could work for this. I've lost fish to what I think was columnaris, but without a microscope and diagnositc testing there's no real way to know. Hopefully someone else can also chime in with experience successfully treating this. 

Simply discus forum lists some options for treatments written with discus in mind, but would work on many fish)- 


Columnaris spp. is a simple pathogenic gram negative bacteria. It is commonly found in soil, water and on healthy and sick fish. It's an opportunistic bacteria attacking sickened, weakened...


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I had that thought that but it was really hard to tell with the symptoms.  Since the maracyn 2 ended I haven't lost any fish but they are still opening and closing their mouths rapidly so it might not have been cured even though the maracyn 2 should've helped.  Maybe I'll try treating for columnaris next but I'll have to tread carefully with the shrimp I have since I know some of the medications aren't good for shrimp.

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