I have put one Rainbow shark into his new tank today, hes been great and seems to like this much better, hes been going round exploring all fine, hes also been trying to ride the filter current 
But i have noticed he has just begun to swim backwards alot, is there any reason for this, or is he just messing?
But i have noticed he has just begun to swim backwards alot, is there any reason for this, or is he just messing?