is less recognizable. The adult gills are made up of smooth, column-shaped filaments, instead. The kidneys have an important role in nitrogenous waste excretion in this species and are enlarged in adult fish. Ecology A. gigas requires breathing surface air to supplement the oxygen it derives from the use of its gills, and as such, is dependent on surfacing every 5–15 minutes to loudly gulp air at the surface. As in other species in the genus, a modified swim bladder that contains lung-like tissue is used for this purpose. The species primarily feeds on fish, although juveniles prefer insects and fish larvae until fully grown. They also consume birds, mammals, fruits, and seeds on the water surface. Spawning occurs in lakes and river channels during the time of low water levels (August to March). After the young hatch from eggs laid in a nest constructed by both parents, the male remains to protect them for a period of about three months. The young reach sexual maturity at an age of four to five years; average lifespan in captivity is 15–20 years. Conservation The species has in the past been heavily impacted by overfishing, exacerbated by their easily exploited habit of surfacing regularly for air-gulping. The IUCN is currently not assigning a conservation status to A. gigas due to a lack of detailed information about population developments. Arapaima fishing was banned outright in Brazil from 1996 to 1999, due to declining populations; since then, both subsistence and commercial fishing have been permitted in specially designated areas, and a sophisticated sustainable management strategy has led to massive recovery of stocks, from 2,500 in 1999 to over 170,000 in 2017. For Bolivia, the paiche as an invasive species is considered a threat to local native species according to reports. Various reports show a correlation between the spreading of paiche and the decline in numbers of native fish species in parts of the Bolivian Amazon. Effects on local fish species populations and on fishing behaviors vary strongly by region. A joint study of the Bolivian government and different research organizations from 2017 points out the necessity to further evaluate the complex environmental and socioeconomic impact of paiche in the country. References Osteoglossidae Taxa named by Heinrich Rudolf Schinz Fish of the Amazon Basin Freshwater fish of South America Fish described in 1822