I know there has been other threads on this but i couldn't really find an answer. My 75 gal has a emperor 400 and 2 large air stones in it so i think that takes out there not being enough oxygen. My 2 sen bichir's are the only ones doing it. My new ornate seems to be fine and isnt breathing hard at all. The heavy breathing does come and go but it doesn't occur at certain times (like after eating or being stressed from another fish or light being on) So does anyone know if i should be worried? All of them are still eating fine and getting air at the top like normal.