Life in a bubble: the role of the labyrinth organ in determining territory, mating and aggressive behaviours in anabantoids

Abstract

The anabantoids are a group of c. 137 species of air-breathing freshwater fishes found in Africa and southern Asia. All anabantoids have a pair of suprabranchial chambers that each house an air-breathing organ known as the labyrinth apparatus: a complex bony structure lined with thin, highly vascularised respiratory epithelium. The labyrinth apparatus allows anabantoids to extract oxygen from air and is a morpho-physiological innovation that has had a dramatic influence on the behaviour of these fishes. Air-breathing influences a wide range of anabantoid behaviours, including territorial displays, courtship and breeding and parental care and also equips these fishes to persist in hypoxic and polluted water. These traits also make anabantoids successful invaders of novel habitats, a global problem compounded by their popularity in the aquarium trade. By reviewing the functionality and evolution of air breathing in anabantoids, this review aims to examine the role of the labyrinth apparatus in modulating behaviour within this group. The anabantoids are a fascinating group and have often been cited as a model organism due to the stereotypical and easily identifiable behaviours that they adopt during social interactions. They also provide a unique opportunity to further our understanding about how fishes adapt their behaviour in response to an extreme environment, whilst limited by their own physiological constraints.

Behavioral and brain- transcriptomic synchronization between the two opponents of a fighting pair of the fish Betta splendens

“…The fighting fish B. splendens is well known for its long fighting duration. It belongs to the suborder Anabantoidei of the perciform ray-finned freshwater fish, which are distinguished by their possession of a lung-like labyrinth organ that helps them to carry out surface-breathing [10][11][12]. This fish has been commonly used to study the biological mechanism of aggression for various reasons.…”

Extrinsic stressors modulate resource evaluations: insights from territoriality under artificial noise

“…The maximum of~40 dB change in sound pressure levels at frequencies of 1-4 kHz (Fig. 2d) under noise treatment reflected nominal low-magnitude underwater noise in areas near terrestrial city traffic or with light shipping [49,67] and matched profiles eliciting response in other gouramis (maxima of 5 kHz; 20-40 dB changes [47,68,69]). The lid and noise conditions were experienced by focal animals for 10 min before contests, allowing for both acclimation to the lid and assessment of noise conditions, and maintained only for the duration of each staged contest.…”

Wild Betta fighting fish species in Thailand and other Southeast Asian countries

“…All these freshwater Betta fish have a common feature that is important for their survival in water with low oxygen content [25]: some can even survive in water with near-zero dissolved oxygen. They can gulp air to put molecular oxygen into the labyrinth organ inside the head region.…”