The arapaima, Arapaima gigas, is one of the largest bony freshwater fish in the world. Just like a suit of armour, its broad scales protect it from piranha bites.
A rare fact with fish: the males and females build a nest and protect their young together.
The arapaima can suffocate if it does not come to the surface every ten to twenty minutes to breathe. Although the young have gills which work for a few days, they lose part of their function in adults. So the adults use their swim bladder (œsophagal diverticulum in fish) as lungs.
Its flesh is very tasty, so it is intensively fished.