The tambaqui (tahm bah KEE) life cycle follows the flow of the floods. The young are born in the river channel and are carried by high water into the floodplain, where they live in floating meadows, eating grass seeds. In low-water season, their nursery is the floodplain lake, where they eat microscopic plants. At 4 or 5 years of age, they move into river channels and spawn at the start of the annual floods.

During the floods, tambaqui use their keen sense of smell as well as their vision to find their favorite fruits and seeds in the forest. They especially love rubber tree seeds, crushing them with their large molarlike teeth. (Tambaqui and a few of their close relatives are the only freshwater fishes with such teeth). Tambaqui feast throughout the floods, then move with the receding waters back to the river channel. After the floods, 10 percent of a tambaqui's weight is fat. The fish live off fat stores and don't eat much until the floods come again.

The tambaqui is one of the most important commercial fish species in the flooded forest. But unsustainable fishing practices have caused populations to plummet. Juveniles - which haven't had a chance to breed yet - are heavily fished in floodplain lakes. Furthermore, drastic environmental changes that people have made to the flooded forest - through logging, clearing for agriculture and ranching, and damming - have in many areas destroyed the habitats essential to the tambaqui's life cycle.