Why does my cory swim up and down the side of the tank?

It is a very stange malady cslled bubbleitis....
cory's do it, loaches do it, tetra's do it....when u have several different breeds of fish i.e. clown loaches, cories, kuhli loaches guppies and bettas doing it...it can give you the 1970's (I am old i remember those days) dayglo neon orange neon green stare at this mesmerization affect for humans....not exactly sure why the fish do it....but they do :)
Be worried if one of the fish starts wearing a rassfa hat and they start saying wow man..coooool
 
Thank you all for the reply.
I am glad to know that it is just a normal behavior.
I have never thought that watching a catfish could be this entertaining!
 
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