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Hi all,
We have had this L160 just over a year now. Shortly after we got her she developed a kind of slime on the dorsal fin. We kept monitoring her but she was fine, eating etc and the other L160s in this tank didn't seem to have the same symptoms, so we let her be. Over the last year these slimy patches became more (5-6) but again, contained in size. Yesterday we noticed a white cyst appearing on all of them. The fish is fine in every respect, her behaviour is normal, she is eating fine and she has grown considerably. Having said that, this is certainly not healthy. We don't want to treat the tank because none of the other fish have any symptoms whatsoever so we will have to take her out and treat her separately. Can anybody identify what it is?




Thanks.

Looks like fungus to me. Shouldn't be too difficult to cure, but you may want to figure out why the fish got it in the first place - as it's not "normal" for fish to catch these things.

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Mats

It is not fungus. It is a thick slime coat with a cyst or something developing in it. It does not spread to other animals either.

Thanks.

I agree, that doesn't look like fungus to me either.

My first thought was an early stage of columnaris - it may produce small raised white pustules and heavy slime secretion similar to the photo - but that's just because I've been seeing so much columnaris recently that I'm now inclined to see it everywhere. The placement of and general look of the pustules on your fish doesn't fit columnaris.

On second thought I think it's more likely to be a protist parasite than a bacterial infection. There are other possibilities, like sporozoans, but my first suggestion would be some sort of parasitic ciliate, depending on scale maybe even some strain of good old-fashioned white spot, although the heavy slime secretion seems unusual.

To identify the parasite you'd likely need to do a biopsy. Scrape one of the spots onto a microscope slide, add some water, and have a look at it under a microscope at 40-100x magnification. There are good identification guides on the net, e.g. this one:
http://edis.ifas.ufl.edu/FA041

If that is not an option, I'd suggest medicating against protist parasites. Personally I'd treat the entire tank with 25 ppm formalin for a couple of weeks, but any medication against white spot should work, with the caveat that some catfish are sensitive to some medications. If the medication works you should see effect within a few days.

Thanks guys. As Barbie rightly observed, the skin of the fish is intact and we can confirm with absolute certainty that she is not the lowest in the pecking order in her tank; in fact she can be a right little bully when it suits her. We are surprised as we first saw signs of this a year ago (about a week after we bought the fish) so it must be a Rio Para free present .... Again, it is odd that it has taken so much time to develop and that it has not spread to any of the other fish.
The microscope suggestion sounds very appealing - we don't think the fish is in immediate danger which is good because we can avoid unecessary medication and experiments. If nothing else, we can find out what the thing is and get it listed on the forums for all. We'll keep you posted.
Thanks again.

It looks very similar (though not quite the same) as an Epistylus super-infection you see sometimes on imported Corydoras.

I have never personally seen Epistylis, but as that's a parasitic ciliate it, too, should be sensitive to ich medication.

EDIT: Also I thought Epistylis looked more like this.