Date of Award


Document Type



Environmental and Forest Biology

Thesis Advisor

Donald J. Stewart


Arapaima spp. are large, commercially important but poorly studied freshwater fishes endemic primarily to the Amazon and Essequibo rivers of South America. Arapaima are obligate air breathers with a modified lung-like swim bladder. Surfacing to respire exposes arapaima to a heightened predation risk, especially the small juveniles. Surfacing in synchrony could reduce predation risk of individual arapaima. Synchronous breathing has been observed with many air-breathing fish, but it has not been documented with arapaima. Many fishes also are known to produce characteristic sounds to startle predators when attacked, but such sounds have not been reported for arapaima. An investigation of predation defenses of juvenile arapaima was conducted by quantifying breathing frequency patterns over a diel cycle. Also, the ability to produce startle sounds was evaluated by simulating predation (i.e. grasping the fish). Young arapaima exhibited synchronized breathing throughout the day; mean number of arapaima per breathing event was significantly higher (p