james15 james15
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  • Posted on: 8/11/2012 16:15
harlequins with mouths stuck open #1
Just bought three harlequin rasboras on Monday (I already had three so I was bringing the shoal up to six). Added them to my tank in the usual way (float in bag for 20 minutes first etc.). I didn't quarantine them as the LFS quarantines them anyway, so I didn't think it would be necessary, although I'm beginning to this I might be wrong there! Yesterday one of the new ones died, and today one of the remaining two has it's mouth stuck open, as does one of the old ones. Any ideas? Water quality is fine, I've tested everything.
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  • Posted on: 8/11/2012 16:25
Re: harlequins with mouths stuck open #2
Can you look very closely at the affected fish and see if there's any sign of inflammation or white fungus on the lips or inside the mouth? Can you also post water test results please?
james15 james15
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  • Posted on: 8/11/2012 16:33
Re: harlequins with mouths stuck open #3
Water test results:

Ammonia-0
Nitrite-0
Nitrate-20ppm

I'll just go and have a close look at them now.
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  • Posted on: 8/11/2012 16:37
Re: harlequins with mouths stuck open #4
It gets worse... the older one which was affected has just died. On the plus side this gave me the opportunity to examine its mouth very closely - no sign of any inflammation or fungus. The inside of its mouth was white - not sure what colour the inside of a fish's mouth would usually be? But nothing "fluffy" like fungus as far as I could see.
james15 james15
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  • Posted on: 8/11/2012 16:46
Re: harlequins with mouths stuck open #5
All other species seem perfectly healthy btw - only the harlequins are affected.
Fishlady Fishlady
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  • Posted on: 8/11/2012 16:51
Re: harlequins with mouths stuck open #6
Does the inside of the mouth look slightly "milky"? The mouth should be a pale pink colour and I suspect the Harlequins have columnaris which is a nasty bacterial disease. It often shows as cottony areas on the mouth or white patches like white mould on the skin, but it can sometimes be internal with less clear symptoms. The whiteness inside the mouth and their holding their mouths open along with rapid death does sound very much like it though.

Columnaris (or cotton-mouth) is caused by a bacterium called Flexibacter columnaris and is very contagious. It is difficult to treat successfully, but first line of treatment would be eSha 2000 to at least try and minimise the spread. Often anti-biotics are the only answer, but would involve a prescription from a Vet as they aren't available over the counter in the UK.

Do a large water change, remove any carbon from the filter and start treatment as soon as possible. FX for them.
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  • Posted on: 8/11/2012 17:27
Re: harlequins with mouths stuck open #7
Sounds like that's probably what it is then. I'll have to see what I can do then.
Lesson learned - I will quarantine all new fish in future.
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  • Posted on: 8/11/2012 17:30
Re: harlequins with mouths stuck open #8
How big a water change btw?
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  • Posted on: 2/12/2012 17:45
Re: harlequins with mouths stuck open #9
Sorry it's been a while. Update on this situation: two more harlequins died the night I started this thread, but since then, no more have died or even shown symptoms. The remaining two harlequins are fine (apart from being a little lonely - I'll get them some friends soon) and all other fish remain unaffected. So it looks like whatever it was, it wasn't columnaris. I've treated the whole tank with eSHa 2000 just to be on the safe side though. I was lucky(ish) this time, but I've learned my lesson - I will quarantine all new fish from now on, not just rely on the fact that the LFS has quarantined them.
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  • Posted on: 2/12/2012 20:05
Re: harlequins with mouths stuck open #10
Glad you've had no further losses.