Sleeping cory???

[BobTheDog]

My dogs woke me up to go outside at 3AM last night. So, while I was waiting for them, I went over and peered into my aquarium to see if I could spot my pleco (he only comes out of his cave at night). Anyway, my skunk cory was floating at the surface, upside down!!! I assumed he was dead, so I got out the net to retrieve his corpse. Surprise, surprise, he starts flopping around as I pulled the net out. Is this normal? Moost of my fish appear to sleep when the lights are off at night, but they usually drift along, UPRIGHT in the current. Have never seen one just floating upside down at the surface.

 

[Inchworm]

Hi BobTheDog

This is not normal behavior for a cory.

While they often dart up to the surface to grab a gulp of air, they do not ordinarily spend much time there. The oxygen they get this way is a supplement to, not a substitution for, oxygen they take in through their gills.

The usual reason that a bottom dweller lurks around at the top of a tank is because there is something wrong with the conditions at the bottom. Perhaps he cannot get enough oxygen there, so he goes to the top since there is more at this level.

I would immediately do a good vacuuming of the gravel and a substantial water change, just to be on the safe side.

If your water does not circulate enough from just the filter, you might want to consider adding an airstone.

Low oxygen content in the water is one of the conditions that promote the growth of Columnaris bacteria, and this could result in finrot and bacterial infection, so be on the look-out for this.