Strange cory cat behavior

[james20]

Yesterday I got a few Cory Cats for my 20 gallon tank. I know they like to sit on the bottom some times and then swim around, and mine do that but... not on the bottom sometimes. They swim up the tank walls and just stand still up against the top corner of the tank. Is this normal? All my other fish are fine.

[Stlouisfish]

They will periodically swim up the tank walls to breathe air and then go back down to the bottom.

[james20]

Ok now one of them just sits all the way up between the glass and the back of the filter. He isn't stuck or anything, and every time I make it swim down from there he goes back up and sits between the back of the filter and glass. What's up with this?

[Goes to 11!]

Ok you didn't QT apparently. Here's a few questions for you.

How many is 'a few'? Is your tank cycled? How did you acclimate? What are your tank parameters, What is your filtration and other stock.

[Indian Woods Angels]

Corys are very strange little fish. They react to changes in the water that trigger spawning responses. Sometimes these responses look like they are sick. They will go limp or numb and look like they just had a heart attack or something. Sometimes when placed into a new tank they will have these odd responses. They also will spawn up the sides of the tank glass. They often will hover in places along the tank walls. They also like water a bit cooler for the long term. 78 F or so. They do go to the top for air. They seem to enjoy a current. Keep an eye on them and their respiration.

[steeler58]

Ok now one of them just sits all the way up between the glass and the back of the filter. He isn't stuck or anything, and every time I make it swim down from there he goes back up and sits between the back of the filter and glass. What's up with this?

Did they stop the odd behavior?

[ddavis1979]

My peppered corydoras do this all the time. None of my other cory cats do it. It certainly looks like a sign of stress, but i have yet to figure out what it is. They will find objects close to the surface and sit on them. It may be a response to other tank mates harrassing them.

In any case none of my fish have died, so I just let them do it....going on 4 months now.