Hello. Couple weeks ago I had 3 Panda Cories. These 3 liked to glass surf on the ends of the tank a lot. Up, down, up, down over and over. Then I added 3 more. This behavior drastically lessened. About a week after that disease hit the tank and I lost 3 of them. I fully believe that they were the new 3. The tank is now undergoing treatment. The remaining 3 are starting the glass surfing again. Is the answer for why they are doing this the obvious answer? Inadequate school? If I add 3-5 more (after quarantine this time) should this behavior lessen or stop? Also, in the end I really want Sterbais in this tank (20 long by the way) for temp compatibility reasons. Should I try to get 6 Pandas before moving them? Or start adding Sterbais, move the Pandas and up their numbers, and then finish the Sterbai school?