The yellow anaconda (Eunectes notaeus), also known as the Paraguayan anaconda is a boa species endemic to southern South America. It is one of the largest snakes in the world but smaller than its close relative, the green anaconda. Like all boas and pythons, it is non-venomous and kills its prey by constriction.
Adults grow to an average of 3.3 to 4.4 m (10.8 to 14.4 ft) in total length. Females are generally larger than males, and have been reported up to 4.6 m (15.1 ft) in length. They commonly weigh 25 to 35 kg (55 to 77 lb), but specimens weighing more than 55 kg (121 lb) have been observed. The color pattern consists of a yellow, golden-tan or greenish-yellow ground color overlaid with a series of black or dark brown saddles, blotches, spots and streaks.
The species appears to have been introduced in Florida, although it is unknown whether the small population (thought to derive from escaped pets) is reproductive.
The yellow anaconda has few predators. Juveniles and the occasional adult may be taken by caimans, larger anacondas, jaguars, cougars, some canids such as the crab-eating fox, mustelids, and raptors. The species is also hunted by humans for its skin.