BN not moving, swimming with no sennse of direction.

[yeattsca]

I have a large female BN who all of a sudden stoped movong. So I picked her up thinking she had died and she tried to swim away and when she did she cork screwed streight to the bottom. I have no Idea whats wrong. This has happend only once before when i was a nube to the hobby and decided to add a pleco without aclamating it. There is drift wood in the tank, its pine but I don't think thats the problem, it doesn't efect my other plecos. She has been living in the tank for well over a week and a half so its not pH poisoning and the male I got with her is doing swimmingly.
Regretibly I have waited till now to post this so by the time I get a response she may very well have died but i would like to know what I should do with my outher plecos so that they dont meat that same demise.

[andywoolloo]

what are the parameters of your tank? Ammonia, Nitrite, Nitrate, PH, temp...

I would do a 50% water change in the mean time.

[MatsP]

I've only ever had this happen to very small babies - but I'd unfortunately think this is not easily corrected.

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Mats

[yeattsca]

Thanks guys. I tried a 50-60% water change but it was to no avail.
I still would like to know exactly what happend.

[MatsP]

I'm not sure - I think it's something neurological, which would point towards some sort of toxic substance. But someone else may have a better idea.

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Mats