At Least 20 of the 30 alien fish species brought into Bangladesh over seven decades for aquaculture the rearing, breeding and harvesting of the species in controlled aquatic environments coming to have harmed natural fish farming after their escape to open water suggests that there has been a continued negligence on part of the government in oversight on the import of fish for farming. The species, which are highly invasive, are said to have rapidly invaded open water, causing the extinction of indigenous fish and the destruction of aquatic ecology. While the farming of such alien fish species, which are less rich in nutrition than the indigenous fish, has increased the overall fish production, it has put food security in jeopardy and has threatened a large number of people who live on fishing and fish farming. The alien fish species are also said to contain a high level of heavy metals that are detrimental to humans. The exotic varieties of fish are popular for aquaculture because of their capacity to grow exponentially in the worst environmental conditions and their escape to open water has, therefore, harmed naturally breeding indigenous varieties that struggle to cope with challenges such as river encroachment, shrinking waters and industrial pollution. The species of African sharptooth catfish, or African magur as it is locally known, banned seven years ago, and red piranha, banned 13 years ago, often passed off as the pomfret, are still grown illegally, especially in pockets of floodplains in the dry season, and sold on the market in Bangladesh. Tilapia, introduced from Thailand in the 1950s that was made popular in the 1980s, has become an obstacle to local fish in Bangladesh’s south and west. The common carp, which is a bottom feeder that constantly pokes at the river bed making the water turbid, burying fish spawns and reducing sunlight penetration, and the grass carp, a weed eater that reduces aquatic flora to a large extent, causing a decline in dissolved oxygen, have made the existence difficult for indigenous fish. The common carp also erodes the river bank where many indigenous fish nest during the summer. Nutritionists say that a kilogram of mola carplets can equal the amount of Vitamin A contained in 200 kilograms of silver carp. Exotic fish have also brought in diseases with them and the two of the worst ever such diseases are red spot disease and white spot syndrome. Red spot disease is said to have been a reason for the decline in the indigenous species of spotted snakehead, snakehead murrel, walking catfish, swamp barb and Indian carp in the 1980s and white spot syndrome has harmed the shrimp industry. It is long past time for the government to have a proper oversight on fish farming, especially of the species that have been introduced with hopes for a better aquaculture production but which has, in effect, harmed indigenous varieties. The government must, therefore, shore up the issues before the indigenous varieties that are at risk become extinct. While this will help the government to better public heath, this will also ensure a harmless protein intake.