Part 4/9:
Traveling from the Alps, the waters wind their way to Lake Constance, one of Germany's largest lakes. This body of water, shaped by glaciers and rich in sediment, hosts a variety of aquatic life, including the elusive wels catfish, a massive predator that prefers the darker depths of the lake. The area also has an intriguing cast of characters, from the small sticklebacks guarding their nests to the invasive pumpkinseed fish, showing the complex interplay of life beneath the surface.