The Giant Arapaima, also called Pirarucu, is one of the world's largest freshwater fish, reaching
over 3 metres, and a most unusual fish in its need to breathe air.
Native to deep water of the Amazon Basin, including tributaries and lakes, it used to be thought
the only species in its genus, but lesser species have since been classified.
It's head looks pre-historic - almost like an engraved fossil in parts - and has an aerodynamic shape. It
has a labyrinth organ in its mouth rich in blood vessels for breathing surface air in oxygen-depleted deep waters. The tail end
is flecked with bright red.
It can breathe underwater through gills but needs to supplement that with surfacing to breathe air regularly.
It can weigh some 200 Kg. It eats fish, crustaceans and even small birds and fruits.
The head and scales have "mineralised" armour to protect from piranha.