Manipulation through invasion is a major problem inmost of the port areas in recent world. Mongla is animportant sea port that has accomplished theactivities like import and export of various goodsinside and outside Bangladesh. The process not onlyinvolves the moving of goods, it also carries theinvasive species purposely or accidentally whichinvading to the new location of the Mongla port areathrough exploration and colonization with varietiesdiversity and scale. The research reveals thatballast water of cargo ships is one of the means ofinvasion of the coastal waters of Mongla Port.Aquaculture is another reason of invasion due tointroduction of many exotic fishes and shrimp speciessuch as Pangus (Pangasius hypothalamus), AfricanMagur (Clarias gariepinus), Tilapia (Oreochromismossambica) and Nilotica (Oreochromis niloticus) etc.that have the active roles for altering the aquaticecosystem of Mongla Port. Finally, the research alsofinds out some possible environmental impacts causedby those invasive species.