labyrinth organ

plural labyrinth organs

1. biologyAn organ common to fish of the suborder Anabantoidei that enables them to breathe air.

   The labyrinth organ fills most of the opercular cavity and is positioned behind and above the gill chamber and extends into the suprabranchial space; hence the name suprabranchial organ.

   2008, Tim M. Berra, Freshwater Fish Distribution, page 480

   2 more examples

   The labyrinth organ may work a bit like a lung, but it is an entirely different solution to the problem of how to remove oxygen from air.[…]The labyrinth organ is an effective adaptation to low-oxygen habitats.

   2002, Gary Elson, Oliver Lucanus, Gouramies and Other Labyrinth Fishes, page 6

   Anesthesia of fish with labyrinth organs (bettas, some gouramis, etc.) should be approached with caution. Owing to the unique anatomy of the labyrinth organ (enables fish to breathe atmospheric oxygen) and the gills of these fish (thick lamellae and ecreased lamellar surface area), it is possible to "drown" the fish if an overdose of an anesthetic agent is given.

   2012, Helen E. Roberts, “MS 222 Anesthesia”, in Jörg Mayer, Thomas M. Donnelly, editors, Clinical Veterinary Advisor: Birds and Exotic Pets, page 513