[Jah410]

Hi guys,

I've had some Cardinal tetras doing great for about 8 months now. I noticed they are acting strange and skidish recently and found 2 of the 11 dead.

I just upgraded my filter the other day, but am wondering if what could be stressing them/killing them is a temperature drop.

I left my window open the other night since it was cool outside and my tank temperature (with a small heater) may have dropped from 77ish to around 71. I know that they prefer a higher temp than that but wanted to ask if you thought that alone could have caused these problems.

Water is pristine, heavy plant scape now even better filtration...

 

[Preeths]

Did you replace the old filter with a new one, it could just be that you are having a ammonia spike since the beneficial bacteria are not present in the new filter, basically you have started a new nitrogen cycle.

 

[monkeyruler90]

Definitely not that sensitive to a minor temp change
but i agree that I think the main issue is the filter upgrade that probably upset water parameter stability.

usually it's good to run the new filter with the old media or run both filters at the same time until the new filter is cycled.