Invasive species are among the major environmental challenges facing ecosystems worldwide because of the changes they can cause to natural balance and biodiversity. They are living organisms that move beyond their natural geographic range, either intentionally or unintentionally, and become established, reproduce, and spread in a new environment. They may cause environmental, economic, or health-related harm. It is important to distinguish between introduced species and invasive species, as not all introduced species are invasive. A species is considered invasive when it has the ability to spread and cause adverse effects in the environment in which it becomes established. Invasive species reach new environments through various pathways, including international trade, the transportation of goods, shipping, and ballast water, as well as the trade in plants and animals and the release of certain organisms into the wild. Changes in climatic conditions and disturbances to natural habitats may also create favorable conditions for the establishment and spread of some of these species. When they enter a new environment where some of the predators, parasites, or diseases that regulate their populations in their native habitats are absent, their populations may increase rapidly, allowing them to become strong competitors with native species. One of the most significant impacts of invasive species is their competition with native organisms for essential resources, such as light, water, food, shelter, and breeding sites. This competition may lead to declines in the populations of certain native species or reductions in their geographic distribution, particularly those with limited ecological ranges or specialized requirements. Some invasive species may also prey on native organisms, transmit pathogens and parasites to them, or alter the composition of biological communities and food-web relationships within ecosystems. The effects of invasive species are not limited to living organisms; they may also extend to the physical and chemical characteristics of natural habitats. Some invasive plants can form dense vegetation cover that prevents light from reaching other plants, while other species may alter soil properties, nutrient cycles, or water movement. These changes can disrupt ecological processes essential for ecosystem persistence, including vegetation regeneration, food availability, and the provision of nesting and breeding sites. A well-known example of an invasive species in aquatic ecosystems is water hyacinth (Pontederia crassipes), formerly known by the scientific name Eichhornia crassipes. It is a free-floating aquatic plant that spreads rapidly under favorable conditions. It is characterized by broad leaves and swollen leaf stalks that help it float on the water's surface. When sufficient nutrients and suitable temperatures are available, it can form dense plant mats that cover extensive areas of rivers, lakes, and waterways. Al-Mustaqbal University – The First University in Iraq