# Otocinclus external abdomonal 'blister' help?



## jamesandrewgreen (26 Jun 2012)

We have just had to euthanize one of our Otocinclus and would appreciate if anyone could help with our diagnosis / post mortem.

We came home to find one of our Otos clinging to the back corner of the tank with its head partially out of the water. On closer inspection we found the Oto to have severe abdominal swelling as well as what appears to be a blistering of the skin around the anus, and a large red lump clearly visible inside the blister, between its anal fins . The fish appeared very stressed and in discomfort, trying to lever itself out of the water wherever it could and with very fast gill movement. After some frantic but inconclusive research we decided to euthanize the fish.

Has anyone seen this kind of thing before? The main worry is that the cause of this may remain in the tank and effect our other Otos. Any help would be greatly appreciated!

We have had a group of 9 Otos for 3 weeks in a partially new tank set-up (cycled tank/water/filter/equipment, just re-scaped). The fish were quarantined for 4-6 days after transportation and before entering the tank, which had been fully tested. About 1 week after introduction to the tank one Oto was found dead with no visible symptoms. At the time we put this down to stress of transportation and moving, given Otocinclus often delicate nature. About 5 days ago we added a second external filter to the set-up.
The attached images were taken just prior to euthanasia.

Our current water parameters are as follows:

PH: 7.4
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 10 ppm

125L,
25 degrees C,
7x Otocinclus & 1x Nerite snail,
1x Ehiem Ecco Pro 2034,
1x APS EF1400


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## Otto72 (27 Jun 2012)

Can you post some pictures please.


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## jamesandrewgreen (27 Jun 2012)

It's not very pleasant to look at i'm afraid, but here are the pictures.


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## sr20det (27 Jun 2012)

Can't see any pics


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## jamesandrewgreen (27 Jun 2012)

Hope this works


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## sr20det (28 Jun 2012)

Poor fella. Can't say myself. Hopefully someone will pop on with medical analysis.


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## Tim Harrison (28 Jun 2012)

A probable culprit is a species of pseudomonad bacteria, perhaps _Aeromonas punctata_. They can cause ascites (accumulation of fluid in the peritoneal cavity), patchy or general reddening of the skin, particularly the ventral side near the anus and on the fins. The diseased fish may also be listless with white or ulcerated hemorrhages.
http://www.google.co.uk/search?hl=en&pq ... 80&bih=681


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## jamesandrewgreen (28 Jun 2012)

Troi said:
			
		

> A probable culprit is a species of pseudomonad bacteria, perhaps _Aeromonas punctata_. They can cause ascites (accumulation of fluid in the peritoneal cavity), patchy or general reddening of the skin, particularly the ventral side near the anus and on the fins. The diseased fish may also be listless with white or ulcerated hemorrhages.
> http://www.google.co.uk/search?hl=en&pq ... 80&bih=681



That doesn't sound very nice! Do you think there's a risk to the fish remaining in the tank? If so how can i get rid of it??
Would UV sterilisation be an option?


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## Tim Harrison (28 Jun 2012)

Hi,

If it is _Aeromonas punctatas_, it is a very variable aquatic bacterium which occurs in harmless and pathogenic strains. It only becomes a problem if it takes up residence where it's not necessarily supposed to be i.e. in the case of your poor otto in the peritoneal cavity. 

It 's pretty much the same with all bacterial diseases; and not just for fish but for us too. So I doubt there is any need to worry too much; although it is little consolation to your suffering otto, I think it was simply unlucky, and in this case I am sure you were absolutely right to euthanize it.

If it is what I suspect, and it strikes again the disease should respond to streptomycin or chloromycetin. 

Best bet is a bath. 80 mg of chloromycetin to be dissolved in 1 litre of water. The fish to remain in the bath for 8 hrs; don't add the antibiotic to the tank.

But I might be totally wrong, so don't take my advice as gospel. I am sure there is someone out there who is infinitely more qualified to make a diagnosis, that is other than an ecologist with an ancient parasitology minor.


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## jamesandrewgreen (28 Jun 2012)

That's really reassuring, thanks! any idea where to find 'streptomycin or chloromycetin'? although I hope we won't need it.


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## Tim Harrison (28 Jun 2012)

Folks are always inclined to think that vets only deal with cute furry mammals such as cats, dogs, and hamsters etc, but give them a try, they are always a good place to start, even with fish. You'd be surprised and they can prescribe antibiotics, and other drugs.


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