Life has been generous in its allocation of fish species to the Amazon region. Around 2,000 species are described, but scientists estimate at least another 1,000 remain to be discovered. This is the most diverse freshwater fauna in the world. Miniature living gems such as the tetras provide a source of pleasure for aquarists world-wide. Numerous species are a crucial source of protein for local people and several comprise an important export commodity. Some are fearsome, such as the infamous piranha and electric eel. Others are just plain weird, such as the arowhana, which catches insects by leaping out of the water, and the leaf fish which not only looks like a leaf, but also swims as though it was floating in the current like a dead leaf. About four-fifths of the Amazon fishes are characins a group relatively rare outside the tropics. The other important groups are the cichlids and the osteoglossids. The latter are living fossils and include the world's largest freshwater fish.