Which Australian fish can breathe air using a single lung?

The Queensland lungfish can breathe air using a single lung.

This ancient freshwater fish, also called the Australian lungfish or barramunda, uses a lung-like organ connected to its digestive system. It normally obtains oxygen through its gills, but the lung becomes important when water is warm, stagnant or low in dissolved oxygen.

Queensland lungfish are native to slow-moving rivers and reservoirs in southeastern Queensland, including the Burnett, Mary and Brisbane river systems. They have elongated bodies, broad fins and distinctive overlapping scales, and can grow to around 1.5 metres in length.

The species is a surviving member of an ancient lineage of lungfishes. Unlike some African and South American lungfish, it does not aestivate in a mud cocoon during drought. It also differs from marine fish commonly called lungfish: the Queensland species is entirely freshwater and lays eggs among aquatic vegetation.