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| Yellow snails (Pila sínensis) have been destroyed by many methods but they still develop and damage crops. |
Those strange aquatic animals have been imported into Vietnam to serve different purposes, including 32 species for food production and six as ornamental animals but they have escaped into nature.
According to Le Thiet Binh, Vice Director of the Aquatic Resource Development and Protection Agency under the Ministry of Fisheries, the northern delta has up to 34 strange species of aquatic animals.
The most notable species of strange aquatic animals imported into Vietnam are white-pincer shrimp, yellow snail (Pila sínensis), Mrigan fish, Chinese white tench, black tilapia, streaked tilapia.
Mr Binh said that most of the strange aquatic animals are fresh-water fish. The State has banned the breeding of three species - nutria, yellow snail and tiger fish (Pygocentrus nattereri) – since they can harm the environment.
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| Tiger fish (Pygocentrus nattereri), one of the strange aquatic animals imported into Vietnam as ornamental fish |
Some imported strange species of aquatic animals can’t adjust themselves to the environment of Vietnam like Chinese sturgeon, small-mouth American perch, Europe mudfish, and Europe eel.
Some others are considered to have high economic values like white-pincer shrimp, tilapia, carp, white butterfish with red stomachs, and red-eared turtles.
However, research of 13 remaining aquatic animals which are imported to breed shows that five are good, two are harmful to the environment and the rest have not been determined as being either good or bad.
Mr Binh said that the import of strange aquatic animals has caused some adverse impacts on aquatic biodiversity.
Some local aquatic species have become scarce because their competitiveness for food and accommodations is weaker than the imported ones, for example Vietnamese white chub, Vietnamese mud carp, and Vietnamese carp. Some other local species, for example ca tre, one kind of catfish, has become a hybrid.
If imported aquatic animals are divided into white (harmless), grey (indetermined) and black (harmful) group, there are nine in the white group, 25 in the grey and seven in the black group in Vietnam. The seven in the black category include yellow snails, ty ba fish, European mudfish, tiger fish, red-eared turtles, Cuban crocodiles, and nutria. Three of them have been banned in Vietnam.