White Clouds are sensitive fish when it comes to O2 levels. They need very high levels. It sounds like the O2 levels in your tank are low. That is probably becuase the ammonia and nitrite levels are high. Ineed do some good sized water changes to help protect the fish.
Also they are cool water fisha dn not tropical. So if the temp is high they tend to be listless and hang out at the top where the most dissolved O2 is.