PLANET EARTH Freshwater

Its tropical waters teem with more fish species than any other lake. There are 850 different cichlids（慈鲷鱼） alone, all of which evolved from just one single ancestor isolated here thousands of years ago. These two-meter wide craters（坑） are fish-made. Fastidiously（非常讲究地） maintained by the males, these bowls are courtship arenas（求偶竞技场）. Cichlids are caring parents.** Brooding（孵蛋） young in the mouth is a very effective way of protecting them.



This lake can be a dangerous place. After dark, predatory dolphin fish（鬼头刀，大型鱼类） emerge from their daytime lairs among the rocks. Like packs of sharks（鲨鱼群）, they're on the prowl**（徘徊） for sleeping cichlids. In the darkness these electric fish hunt by detecting distortions in the electric field they create around their bodies. Any cichlid that trenches out will be snapped up.



The floor of Lake Malawi drops 700 meters into an abyss（深渊）. Here, in this dead zone the larvae of lake fly midges（飞蚊） hide out away from predators. In the rainy season they balloon up to the surface and undergo a magical transformation. At dawn the first adult midges start to break out. Soon, millions upon millions of newly hatched lake flies are taking to the wing.