I have a Emerald Cory and I notice sometimes he just swim really fast to the top and go straight back down. Is that normal? Sometimes he look like he is dead since he doesn't move for a long time an then he suddenly does that. Very weird fish.
I thought it was them going to get air??? Maybe I'm wrong.
+1wait....A <---- (singular) cory? corys do like to be kept in a group of +6, (rarely a problem as they are fastidious little fish).