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Another "What's wrong with my fish" Post

1022 Views 10 Replies 4 Participants Last post by  JustJen
I don't know how well the pics convey what he looks like in real live, but this is one of my male diamond tetras. His skin is very splotchy, missing the shininess in big areas (worse on one side than other) and his fins are eaten up (he had long gorgeous fins as of a week ago). He is in a 55 gallon tank with 7 other diamond tetras (was 8, lost one that looked similar a week ago, along with a yellow rainbow), a female Boesmani rainbow, and a small peacock gudgeon. He acts perfectly normal at the moment. Last August, this was a rainbow tank that also housed cories and a couple of stragler mollies. I foolishly had a couple of fish shipped in and didn't quarantine, and ended up wiping out the entire tank except for the two rainbows. All of the rainbows that I lost displayed similar symptoms to this diamond tetra prior to passing. The diamonds were in another tank, but were moved to the 55 about 6-8 weeks ago (in batches over a couple of weeks just to make sure it wasn't too much at once for the bio filter to handle) - well after the issues had subsided. The only things in the 55 at the time I moved the diamonds were the two remaining rainbows. All seemed fine until the first diamond passed last week, followed by the rainbow, now this guy. The tank has an eheim 2217 and gets 50% water changes every 10 days. Ammonia and Nitrite are zero, Nitrate stays at 20 or under. There are no issues with the other 8 tanks in my house, and the diamonds and gudgeon had been in the other tank for months without issue.

Aside from just wanting to know what's wrong so I can hopefully treat it before it wipes out the rest of the tank, I'm curious what would have caused it to rear its ugly head now.


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This guy passed this morning. Still baffled as to what's going and hoping to put a stop to it before it claims anyone else. Any ideas anyone?
Did you add some new into the tank in the past month?
Maybe columnaris if he died that quickly.
The last "outside" fish to enter that tank was in August. I added some shipped in rainbows straight to the tank rather than QTing and wiped out all but a few fish in the tank. The tank ran with just those few remaining fish until I moved those diamonds to that tank about 6-8 weeks ago from another tank (moved over the course of a couple of weeks to make sure I didn't overload the bio filter - water was monitored through the process). Everything seemed fine until the first diamond died a couple of weeks ago, then the rainbow, now another diamond. The symptoms for the ones I lost in August and the ones I am losing now are identical (patchy looking areas on the skin, ratty looking fins, etc. No "3D" sores or fungal spots or anything, no signs of parasites, water quality is good.
Are the patches you're describing just dull or is there anything else notable about them?
Ah, What you introduced in August never went away. I would guess columnaris. You'd have to treat the fish and tear down the tank with bleach or it'll linger in there forever.

Qt is a hassle but this is much more of a hassle.
columnaris if he died that quickly.

fyi for o/p


An 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.

Bacteria can be isolated from gills, skin and the kidneys. For definitive diagnosis, the pathogen should then be cultured on reduced nutrient agar. Inhibiting contaminant growth on the agar by adding antibiotics and keeping the temperature at 37 °C should improve culture results. Colonies are small, 3–4 mm in diameter, and grow within 24 hours. They are characteristically rhizoid in structure and pale yellow in colour.

Ulcerations develop within 24 to 48 hours. Fatality occurs between 48 and 72 hours if no treatment is pursued; however, at higher temperatures death may occur within hours. Other symptoms may accompany the disease, including lethargy, color loss, redness around the infection site, loss of appetite and twitching or rubbing the body against objects.[2]

As Flavobacterium columnare is Gram-negative, fish can be treated with a combination of the antibiotics furan-2 and kanamycin administered together. A medicated fish bath (using methylene blue or potassium permanganate and salt),[3] is generally a first step, as well lowering the aquarium temperature to 75 °F (24 °C) is a must, since columnaris is much more virulent at higher temperatures, especially 85-90 °F.[4]
Medicated food containing oxytetracycline is also an effective treatment for internal infections, but resistance is emerging. Potassium permanganate, copper sulfate, and hydrogen peroxide can also be applied externally to adult fish and fry, but can be toxic at high concentrations. Vaccines can also be given in the face of an outbreak or to prevent disease occurrence.

The bacteria can persist in water for up to 32 days when the hardness is 50 ppm or more.
Are the patches you're describing just dull or is there anything else notable about them?
Primarily just dull, but they do get fairly pale toward the end. There is no visible fungus or anything of that sort.

Ah, What you introduced in August never went away. I would guess columnaris. You'd have to treat the fish and tear down the tank with bleach or it'll linger in there forever.

Qt is a hassle but this is much more of a hassle.
Columnaris was my first thought, but it just didn't look much like the columnaris that I remembered dealing with many years ago. I also had thought that it would have affected the fish that were in the tank during the August - November time frame if that was what it was since it is so highly contagious. Not disagreeing with the diagnosis, just explaining why I initially looked elsewhere for answers...

I certainly know better than to not QT after all these years. I've bought a LOT from this seller and never had a sick fish, and the rainbows that seem to have brought the illness in where part of a LARGE order spanning multiple tanks. I didn't have the QT space to accommodate all of them to begin with, nor did I have a QT tank large enough to realistically house 4 rainbows for a month. Most of the time when I've taken my chances with no QT, it's worked out for me - it was bound to bite me in the butt sooner or later :-\

Thanks for the help! Guess I'll move forward on trying to treat for columnaris and see if I can put a stop to the dying fish.
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Have you noticed any issues such as labored breath or what looks like "coughing" or "yawning"?
No labored breathing or any odd behavior aside from general lethargy in the 24 hours or so before passing. Since the last passing, nothing else has shown symptoms - not that that means anything as it seemingly laid "dormant" for several months before the latest outbreak.
UPDATE: Ultimately, I lost all of the fish in this tank and I'm looking at what to do going forward to make sure the tank is safe to restock. I've seen people say you absolutely have to tear down the tank, bleach everything, replace substrate/filter media/plants, etc. or it will unquestionably come back, no matter how much time passes. I've also read that the bacteria can only survive a little over a month with no host (so, theoretically, the tank would be "clean" in a month). And plenty of opinions on medicating and whatnot that fall between the two extremes. So for those of you who have dealt with what I'm assuming was columnaris (though it never did fit the classic symptoms), what do you recommend as the next steps to getting the tank inhabitable. I want to be smart about it (because I sure don't want to lose another tank full of fish), but I also don't want to strip the tank and have to replace substrate and plants and all of that if there's no reason to.
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