I had a glofish turn "zombie" for a day and a half from being chased. He, too, hovered at the top and didn't even move for food.
Do you have a bully in the tank? Are they schooled, 6 or more? ( Mine aren't, yet )
Adding hiding spots like big (faux) plants might help for the future. They won't hang out or really swim thru the plants but they will go to the plants to escape a chase.
If you have a bully, you can try what I did.... I chopstick chased the bully every morning when he would start the mean (not the brief) chasing of the other 2. It tired him out enough that they got some rest.
I, also, played Debussy and other peaceful music for them. Sound carries better in water than air so don't blast them out.
I've also played Indian Spirit flute music, classical guitar and environmental ocean sounds "music". I think they all enjoyed the peaceful classical music.
Edited: Mine are the glofish danio, I don't have any glofish tetra or barbs.
(Friend of Bill W., One day at a time)