Corydoras are a unique group of fish. Many species will behave this way at first, but once they settle in, it changes. Some take longer. And some revert to this frantic swimming regularly. And the environment (including how many of them there are, same species and mixed) also plays a part.
I had a single C. duplicareus (last one in the store) who swam fairly frantically constantly for a week, then he settled down. After a few months, he was moved into another aquarium, and the frantic swimming started up again and lasted for a couple of months. Last July I re-set my empty 115g and moved him in there along with 3 small corys of the same species (finally found some). He was quiet from day one, and has never resumed frantic swimming since then.
I have a trio of C. panda along with other species in my present 90g. I have had the pandas for more than a year now. They are almost always together, and almost every evening they do the frantic swim up and down one or other walls of the aquarium, sometimes together, sometimes a pair, sometimes individually on different walls. But every evening between 6 and 9, almost without fail, same behaviour. But during the rest of the day, never. The other cory species in this tank never do this.
They seem to have their own personalities, which is one thing that makes them such wonderful little fish. And their ability to turn their eyes which makes it
appear as if they are winking at you is priceless.
Byron.
Similar Threads 
