Dead cory... need help

[Peter99]

I had to euthanize a panda cory because it was doing the spiraling swim. Looking at the dead cory I see that it has lost its tail fin and where the tail becomes the fin its red, looks like internal bleeding. Looks like its bacterial infection of some sort (fin rot?).

I don't exactly know what's going on here, I want to medicate the tank to prevent others from dying, but don't want to medicate if its not necessary.

What kind of medication, if I must medicate, what can I use that will not kill the cories?

I tested the water parameter and amonia and nitrite were undetectable and nitrate was very low (like 10ppm).

On a side note, the water temps reached a maximum of 90F in the past few days, if that's any help.

Thanks in advance.

 

[Blinky]

I'd guess that your cory became succeptable to a bacterial infection from the stress of the temperature changes in your tank. It's hard when the temperature rises like that, there's not a lot you can do to control it. You can try lowering your water level and letting the filter output create splashing on the surface, and running a fan beside the tank so air blows over the surface helps. Keep the lights off, they'll only add to the heat.
If your other fish seem fine, I wouldn't medicate, but keep an eye on them. Make sure the water's clean (seems like no problem with your tank), the fish aren't overfed, and the tank's as cool as you can keep it, there isn't much more you can do. Sorry you lost your little guy.