arapaima

Arapaima gigas, known as arapaima in Brazil and paiche in most Spanish-speaking countries, is one of the largest freshwater fish in the world. Native to the Amazon basin in South America, it plays a crucial role in both its natural ecosystem and local culture and economy.

This iconic species is currently threatened by overfishing and habitat destruction in much of its range. To alleviate fishing pressure, several fish farms have been established in different countries in South America.

Conversely, arapaima has become invasive in some regions, particularly in Bolivia. Originally from Peru, it is believed to have entered Bolivian rivers following a breach in a fish farm.

Sexual dimorphism is relatively subtle. External differences between males and females are not easily discernible, often complicating gender determination without internal inspection. However, males and females can be differentiated by their behavior during the breeding period, where males build and guard nests.

Historically, this species was abundant throughout the Amazon basin and played a crucial role in the diet of indigenous communities. However, since the late 18th century, overfishing for the trade of its dried and salted flesh has significantly reduced its populations. In the 1960s, the species was still common near major Amazonian cities, but it became commercially extinct in these areas by the late 1970s. Despite the ban on commercial fishing in 2001, illegal fishing persists, still threatening the species.

Conservation efforts have been implemented, especially in the Mamirauá Sustainable Development Reserve, where limited and sustainable arapaima exploitation is permitted. These local initiatives have led to an increase in populations in some areas. However, the long-term preservation of its populations on a global scale requires a thorough understanding of its genetic diversity and the establishment of sufficient reserves to maintain a wide genetic diversity.

Recently, arapaima has also become a problem as an invasive species, particularly in Bolivia. Originating from Peru, the species is believed to have entered Bolivian rivers through a leakage in a fish farm. The paiche, as it is named in this region, has begun to colonize local waterways, advancing about 40 km further each year. Its imposing size and voracious appetite pose a serious threat to native fish, either preying on them or forcing them to flee, thus disrupting local ecosystems.