Huddling in the corner

The Koi huddled in the bottom corner-The one on the left (Goldey), middle (Ghost) and right (Zorro) tend to stay at the bottom of the tank. Not sure why this is, but it may have something to do with them coming from a big pond. They are not used to the tank idea, but they will only be housed for the winter and then return to their home for the summer months again.