Water Hyacinth (Eichhornia crassipes)

Water Hyacinth (Eichhornia crassipes) is the fastest-spreading aquatic invasive on Earth, doubling its biomass in just two weeks. These South American mats choke waterways across Africa and Asia, blocking up to 95% of sunlight and depleting oxygen levels below 1 mg/L, devastating fisheries that millions depend on. This is more destructive than Feral Cat (#10) in terms of immediate economic impact, costing an estimated $100 million annually in control efforts across Africa alone, while Feral Cat kills 1.3 to 4 billion birds annually but with less direct disruption to freshwater ecosystems.