[Γιώργος Κ]

Some labyrinth fish have voices!...and the Pearl Gourami is no exception. The fish has a kind of vocalization that sounds like croaking, growling, or cracking tones. This is generally most pronounced during breeding or with territorial type behavior, but whether it has any special function is unknown.

http://animal-world.com/encyclo/fres.../pearlgour.php