 Some labyrinth fish are important food fish, and many others, such as the Siamese fighting fish and paradise fish, are popular as aquarium fish.The labyrinth organ, a defining characteristic of fish in the suborder Anabantoidei, is a much-folded suprabranchial accessory breathing organ.It is formed by vascularized expansion of the epibranchial bone of the first gill arch and used for respiration in air.