Quarantine question corydoras

[ruudvk]

Hey guys, I’ve been away from the forum for a while due to a busy period (bought a house etc. busy busy etc. :p).

I have a dilemma and it would be great if I can pick someone’s brain on the subject.
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In my apartment I had a 150G tank stocked with 9 Stendker red turks, a bristlenose pleco, a school of rummy nose tetra’s and a group of 6 corydoras trilineatus . (Tank journal http://forum.simplydiscus.com/showthread.php?123758-Stendker-grow-out-and-150G-tank-build)

Before I moved, a trilineatus died (picture below), I guess because of the higher temperatures discus need. During the big move from my apartment to my new place, I separated the six corydoras because I felt they were not doing great in the tank. So, I placed these guys in my quarantine tank (100L) and went on the hunt for some sterbai corys. Found them pretty quick through a local guy who breeds them and placed them in my QT with the trilineatus.

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Now, here I need some help understanding what happened. I placed the sterbai in QT in the end of December, the first two weeks they were doing great, schooling and eating together as one group. No visible signs of sickness or disease. Then, the old group of trilineatus started dying off, one by one. Every two or three days one died until I had only the sterbai left. I tested the water, did extra water changes, tried eSHa200 but nothing helped.

Now I have a QT system running for over 5 months with a group of perfectly "healthy" and happy sterbai corys. They never showed any sign of disease, and can’t figure out what went wrong.

Would love to hear your thoughts on the matter, and what might be the best strategy to introduce the sterbai to my main tank (or not).



Cheers, Ruud

[discuspaul]

The deaths of that first group of Cories one after another is somewhat of a mystery, but after several months in QT and the Sterbais are all continuing to do well, one can safely assume there was no cross-contamination of any pathogen from the trileneatus.

So proceed to add one of your discus (the least desirable one) to the QT tank with the Sterbais, and if after 4 weeks or so the discus & the cories are all doing well & eating, you may place the entire QT'ed group of fish into your main tank.

[ruudvk]

Thanks Paul. I guess it is inevitable to use a hero discus in my situation.

Might the die off be explained by differences in bacteria? In that case, would it be advisable to place a couple of rummy nose tetras in the QT? And see what happens?

[discuspaul]

Well, it's basically the discus you want to protect, so one of them must be exposed in QT.
I would leave it that way with the intention of solely ensuring that all the remaining discus in your main tank are not victims of any health issue emanating from the new cories (assuming the sacrificial discus remains healthy through the QT).

[ruudvk]

Going to pick my hero discus this weekend and hope for the best.
Thanks Paul, appreciate the help.

[brewmaster15]

Hi Rudd,

A hero fish is your best option as Paul suggested. Question for you though. By Quarantine do you mean just keep the separate or do you doing any treatments on the new fish? Fish can carry pathogens easily for months and show no symptoms. I am always concerned about worms when adding new stock.... just be aware that you could be adding worms into your discus i guess is my point.
al

[ruudvk]

Hi Al, yes, in quarantine I keep the fish in a separate tank and observe for signs of sickness. I do not treat profilactic for diseases. I only did a treatment of eSHa2000 because of the dying corydoras.

Should I treat for worms first?