Corys dying

[DrRockter]

Hi all,
I set up an 80L tank in November last year. I planted it with java fern on bogwood, an unidentified fern and a some plants which I think are egeria densa. To be honest, only the java fern is doing well. I don't have lots of light - the other two plants may well get taken out at some point.

I've added fish as follows:
Nov12 - tank set up
9/11/12 - 5x neons added
25/11/12 - one neon died
18/01/13 - 2x peppered corys added
08/03/13 - 2x bronze corys and 2x platys added

All the fish were doing really well until a couple of weeks ago. The corys just stoped being active and died one by one. The neons and platys are all fine. One odd thing is that I've been getting zeros for ammonia / nitrites / nitrates. More recently, I've been getting about 2.5 on nitrates. It's difficult to tell, but it looks to be between zero and 5. I'm using an API liquid kit. The most recent test was pH 7.6, amm 0, nitrite 0, nitrate 2.5. So it doesn't look as though poor water killed the corys. I'm a bit puzzled with the water tests though. In my old 27L tank I always got a good nitrate reading. On this tank, I've never seen any ammonia or nitrites and the nitrate has looked like zero for a while. Possible relatively large tank / small fish situation?

Anyway, I was wondering if anyone has any ideas why the corys died? I like the corys and would like some more, but I won't be getting any until I know what went wrong.

The only other problem of note is the temperature. I bought a cheap heater and it keeps sticking and the temp drops every now and then. I've just ordered a new one.

Any ideas?

[Carylnz]

Could have been the fluctuating temperature.
Egeria densa is a coldwater plant which doesn't like higher temps so the faulty heater won't have helped.
Java fern is hardy and copes with low light, as does Anubias sp. Cryptocoyne wendtii, Rotala, Hygrophila and Baopa (babytears) for a start.

[DrRockter]

Thanks Carylnz,
I'll get the replacement heater in. Maybe try corys again once everything has got back to normal.
As for the densa, I've read another post where you've said this plant is cold water. My lfs knew i had a tropical tank and still sold me it!! I'll take it out soon - see if I can get some of the other low light plants you mentioned.

[ady]

that was nice of the LFS to sell you that plant....NOT !!!!

i have a lowlight tank set up too....it contains anubias,java fern,java moss,cryptocorynes and amazon swords....

there is a pic and video of it on the tank talk section.....just to show you what can be achieved in low light.

i use liquid ferts weekly and the crypts/amazons have root fert tabs around them as they are heavy root feeders....

good luck and hope your new corys thrive this time...