I just added another 2 cory cats to my tank, my original 2 are very active. They constantly swim back and forth along the glass and skim the top making waves through the tank, I thought this was due to a few things, finding hiding spots in the rocks along my aquarium backing as they skim along the reflection, exploring boundaries because of the albinos poor eyesight, or seeking other cories (the reflection) to school. When I added the 2 new corys they kind of laze about together, they joined my other 2 in a few hours and they group up sometimes but don't particularly swim in school yet. My original 2 cories? If they are not feeding along the bottom most of the time they are zipping along my glass still, they eat fine and have been there for over 6 weeks seemingly healthy.
They did seem to calm down when I added an anacharis forest for hiding instead of the one lonely cave, when they hit the glass still they run back and forth over and over for a while though.
I am no expert on cories but it seems normal to me, they like to play, they like other cories and they like to feel safe in their hiding spots so this frantic behavior could be a combination of any of these?
Do you use salt in your aquarium at all? If you do I would stop, they are sensitive to salt and a fish swimming in a pattern toward the filter over and over means it is trying to head upstream away from the salt, and vice versa.
