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View Full Version : How long to leave tank fallow after disease?


ACBlinky
05/17/2006, 02:28 PM
I had a pair of clowns in my 21g and after two weeks of treating the female for popeye (Maracyn & Maracyn Two), I suddenly lost them both to an unknown condition. They looked like they were sloughing their slime coat (I assumed this might be a reaction to being on the meds for 13 days), then started breathing rapidly and within 48h of those symptoms starting they both died overnight. Levels were fine throughout and I was doing lots of water changes, but I didn't realize there was another condition affecting them until it was too late.

My question is since I don't know if this infection was viral, parasitic, bacterial or fungal, how long should I leave the tank fishless before attempting to add new inhabitants? There are inverts in the tank that are doing just fine, and levels are good (NH3/NO2/NO3 0, PO4 0.25, 8dKH, Ca 380, Mg 1250). The tank is a FOWLR with ~15lbs of LR, live sand and a HOB filter.

Amphiprion
05/17/2006, 03:42 PM
So you did end up losing them? I am so sorry :(. Anyway, as far as bacteria (and fungi) are concerned, leaving it fallow may not help. Most potentially pathogenic bacteria are in fact usually harmless commensals or natural flora on fish and in aquaria. I suggest maybe a good tank cleaning (a good, large percentage water change may help) and plenty of detritus removal. Cleaner tanks with higher redox potentials may help in situations like this, as well, by reducing possible food sources for bacteria. Fungi should be looked upon in a similar way.

ACBlinky
05/17/2006, 05:35 PM
Thanks. I did lose them, and I'm incredibly sad about it. Last night they looked uncomfortable, similar to what you'd see in an ich-infested fish - some flashing, rapid breathing, etc. - but they didn't look as though they were about to die. First thing this morning I got up ready to go and buy antifungal meds (Lee's suggestion in response to my post in the disease forum) and discovered that they hadn't made it through the night :(
I've cleaned the filter sponge and bio media in SW, and I'll do a large water change this evening.
If it was velvet (the only thing I can think of that causes rapid breathing, cloudy skin, flashing and death in a matter of days) will leaving it fallow help?

Amphiprion
05/17/2006, 06:29 PM
Yes. Protozoans (such as Cryptocaryon, Amyloodinium, and Brooklynella) are not normal commensals like bacteria and fungi. They must have a host to survive, whereas most bacteria do not.

ACBlinky
05/17/2006, 06:42 PM
Okay, thanks. I'll leave it for a month or so before thinking about any new fish - the last thing I want is to see another fish die like that.