Which osteoglossomorph fishes can breathe air at the water’s surface?

Several osteoglossomorph fishes have developed the ability to breathe air at the water's surface, an adaptation that allows them to survive in deoxygenated environments.1

These air-breathing species include:

• Osteoglossidae: Heterotis, Arapaima, and Pantodon.1
• Notopteridae (featherbacks): Chitala, Notopterus, Papyrocranus, and Xenomystus.1
• Gymnarchidae: The family represented by the single species Gymnarchus niloticus.12

This capability is particularly significant for these fishes, as it enables them to inhabit regions such as rivers, lakes, and areas with dense aquatic vegetation where oxygen levels may be low.1