Dying Cardinals

[goldencomet]

I added eleven cardinals about a week ago, and one dead and another
is gasping for air, my water stats are fine
ammonia 0
nitrite 0
nitrate 40
the temp is 26
please help

 

[rockerBOO]

If possible, add a air stone to the water. Seems you have a low O2 level.

 

[thegnu]

how long has the tank been set up. how many and what other fish have you got in the tank

 

[goldencomet]

It's been setup since christmas and has been cycled for a month and a bit
i added 5 cories and two dwarf gouramis not all at once though

Just had one which was gasping fo air die but all the others seem fine and are breathing normally
also the spout on the filter has been turned up for a while to create more oxygen

 

[jonny-5]

To be honest ive always found Cardinals to be very very fussy in any of my tanks unless its been set up for over 6 month period.Just cant understand why? Ive bought them on many occasions and Neons too and from different shops all the time,but they alll die in the first week.I set up a 15 gallon tank for my guppy fry,after 3 months i gave the guppys away(which are still going today may i add) and bought 5 Cardinals,they all died in the first week or so.The tank had been up and running for over 3 months with no probs at all.So left it prob 4-5 months and bought some more and they are still alive today(just there in my 40 gallon these days)Again when i first set up my 40 gallon tried them after 3 months and they all died again in a week-10 days.I left it for 3 more months and bought 10 more Cardinals and some Neons off a mate over a year ago and there all still going today! I know its a bit of a waffle but just letting you know what happened to me.