How do osteoglossomorph fishes reproduce and care for their young?

Osteoglossomorph fishes exhibit a diverse range of reproductive strategies, with many species demonstrating significant parental care for their young. While some groups, such as the mormyrids, appear to provide little to no parental care, others have evolved complex behaviors to protect their offspring.1

Reproductive methods vary by family:

• Nest Building and Guarding: Gymnarchus niloticus constructs a large, trough-shaped floating nest from swamp grasses, where parents guard the young for approximately 18 days. Similarly, the African arowana (Heterotis niloticus) builds a crude grass nest in flooded plains, with the male guarding the young and leading them on feeding excursions. In the family Notopteridae, Chitala chitala clears a bottom area near a submerged object to lay eggs, which the male then guards.1
• Mouthbrooding: Members of the Osteoglossidae family, such as the South American arawana and its relatives, carry their eggs and young within the mouth of one parent.1
• Pit Spawning: Arapaima gigas (pirarucu) dig a spawning pit. The male guards the embryos and, after hatching, the young congregate around his head, likely attracted by camouflage and chemical stimuli, for two to three months.1
• Minimal Care: Hiodontids lay eggs on rocks or gravel in shallow water without building nests, while the African butterfly fish (Pantodon) produces floating eggs with minimal parental care.1