David Attenborough's Natural Curiosities: Ferocious Fighters

Sir David Attenborough examines the mysteries behind some of nature's most fascinating creatures and plants. The Siamese fighting fish is so aggressive it will fight its own reflection until it is exhausted. Recent research shows that the fighting behaviour varies and depends on the personality of the fish. Male kangaroos were once pitted against humans in the boxing ring - the most impressive male kangaroos are solid blocks of muscle with a kick that can kill.