cories dieing with reason

[irishfishkeeper]

this is my 5th cory to die in a couple of days without a reason.my water is fine too
ammonia 0
ph 6.4 a little lower than normal
nitrites 0
nitrates 30

their all bronze cories none of then have showed any signs of sickness
so i don't know why their dieing.

[dave]

How long have you had them?How long has the tank been established?Where they bought together?
I know you said there was no sign,but was their any discolouration,even slight?

[irishfishkeeper]

I bought all 8 of them together from the same pet shop now i must admit its not a very good pet shop but i bought them at least 7 months ago. i am now down to 1 panda cory left out of 8. I noticed with the last 2 to die were very lifeless and breathing very fast so i added an air pump.Dave no discoulouration at all.Would not having an air pump in my tanks maybe cause this?

[jackpike]

Is there any other fish in the tank with them?

[irishfishkeeper]

jackpike said:

Is there any other fish in the tank with them?

None at all. I was hoping to breed them soon thats why they had their own tank.

[jackpike]

I don't believe, a lack of oxygen in the water has killed them because corrys would take atmospheric oxygen to breath if that was the case. Its more likely that some kind of toxin, pathogen or stress has killed them.

[karen]

IFK have you tested your water since the deaths? Also double check your test kit in case its out of date. How long have you had your breeding tank set up?

[irishfishkeeper]

I have tested again and everythings still fine. Breeding tank has been set up about a month now.

[anthony]

Have you checked the temp of the tank. I doubt its toxins as all of them would be dead by now.