The largest member of the bony tongue fishes, the pirarucu or arapaima is a prehistoric predator. This species is an ambush predator that sits and waits for unsuspecting prey to swim close enough to inhale with a powerful suction into the hard rough plates inside its mouth where they are crushed for swallowing (hence the “bony tongue” reference). These fish also have a pseudo-lung, a specially adapted swim bladder that allows gas exchange through capillaries that extract oxygen from atmospheric air. This means that arapaima are obligate air breathers, so they can drown if they do not go up for air every 10-20 min. They have a muscular streamlined elongate body, with a dark green color that can vary to golden yellow, with fire red or blaze orange markings. Their scales are huge and made up of very hard chitin, which gives them an armor-like cover that protects them from predators when in juvenile stage. Arapaima have adapted to withstand low quality water, with very low dissolved oxygen and when water levels recede, they can stay back in lagoons where other predators must leave and only small fish and juveniles are able to tolerate water quality parameters. This allows them to feed extensively in what other fish use as their nurseries. These giants are some of the fastest growing fish in the world, able to grow 13-15kgs in 14 months! Where prey is plentiful, they can grow up to 2.5mts or more and weigh above 200kgs! Pirarucu means “red fish” in the local native language. These monsters will eat flies, generally streamers that are stripped slowly down in the bottom to mid stratification of shallow lagoons or rivers in Amazonia.