Corydoras paleatus (peppered cory) death

[jasonG75]

Hey guys this morning I found 1 peppered cory swimming in circles upside down and another just laying there. (eventually died) The other seemed to straighten up but not 100%

So I did my water test (liquid)
0 Ammonia
0 Nitrites
25 ppm Nitrates
pH 7.5

55 gal
sand substrate
Cascasde 1000
Heat 80

Now Tuesday I removed my Activated Carbon and replaced it with Purigen (The Bag), other than that there has been NO other changes. And I dosed Pottasium (sp)

How do 2 of the same breed just UP and die?

[fishorama]

Lots of things are possible, bacteria? tankmates? How long did you have them? Any new fish?

[jasonG75]

Tank has been setup up for a year. These were the first 6 fish I added to the tank after the cycle. No other fish messing around near the bottom, and no new additions -- Well I added 2 Indo Flying Foxes the other day, very tiny and smaller than the ottos.

[dbosman]

Did you quarantine the new fish for a few weeks prior to introducing them into your tank?

You said you added Purigen. If this was new container, did you follow the directions on the packaging?
If it was a regenerated bag, did you perhaps not get all the chlorine out?

[jasonG75]

No I did not Q. My supplier, (not box store) has healthy fish and guarentee ick or disease free. They actually Q them for a week before they sell them.

Rinse and insert into filter (in my case middle basket in my canister) Just installed it.

[Chrisk-K]

A new Purigen Bag doesn't kill the fish. Peppered cories are tough guys and something must have happened.

Did you accidentally overdoes Potassium? If not, the new fish probably introduced a disease. One week QT done by your LFS is too short.

[jasonG75]

1 capful per 40 gallons...

Then why wouldn't I see any effects from the other fish? Other fish have been fine, added these Monday.

Also I have been eyeballing then for atleast a month, so I know they were ok...They were housed in a planted tank.

[jasonG75]

Crazy thing....AGAIN....I get home from work and the lil bugger is swimming around ( laying there. (eventually died)) this one. He was on his side when I left to go to work and I was going to fish him out (no pun intended) when I got home.

[fishorama]

Fish can be carriers of disease (or parasites) that they are not dramatically effected by. Some fish are more susceptible than others. 80F is a bit warm for paleatus (59-77F according to planetcatfish) & bacteria usually like warmer temps.

I'd go with daily or every other day water changes & just observe for now. Maybe something was up with your water, there's many more factors than we can easily test for.

[jasonG75]

Water changed scheduled for Sunday..

All my current stock has come from this place, and I don't have a holding tank...thinking about one when I setup my 75.
Current stock consist of
3 Marble Angels (2F / 1M)
7 RummyNose
6 Cardinals
3 Ottos
2 Indo Flying foxes
6 Peppered corys
4 Kuhlis
1 Dojo
1 Brislenose
1 Female red betta

And a whole bunch of plants....its a planted tank.