Every time I do water change(twice a week) my calvus get really stressed out. I make sure the water is the same temp and I use dechlorinator right away. The water changes don't bother my Comps or Frontosas in the tank just the 3 black calvus. A lot of times they end up having their mouths stuck wide open for hours most of the time into the next day than they snap out of it. Does anyone else experience this. Any tips on how to avoid this?