The original text mentions invasive species in China, which are often associated with crayfish and tilapia, but these species may not be considered a successful invasion, but have become a delicacy on the table.
There is a fish that has been breeding in the southern waters of our country for more than 40 years, and it is mistaken for grass carp, and it is wheat dace. The story of the wheat dace is full of mystery and exploration, and its status in our country is similar to that of the grass carp, but few people know its true identity.
A fishing friend in Guangzhou once caught two unusually strong "red-eyed grass carp" while fishing in the Pearl River. These fish have whitish eyes, snow-white scales, and only the eyes are red. Despite being similar in body to grass carp, they are actually wheat dace, a species native to Bangladesh and India. As early as 1982, wheat dace was introduced in China, with the intention of enriching China's aquatic resources. However, due to its resemblance to grass carp in appearance, it has long been mistaken for a variant of grass carp.
Wheat dace is known for its ultra-fast reproduction rate and strong ability to survive. Once mature, it can lay 10 to 150,000 eggs at a time, plus a lifespan of up to 12 years. In addition, as they age, the number of eggs they conceive increases. These characteristics have led to the rapid expansion of dace in the waters, putting pressure on the survival of indigenous fish species.
Although the wheat dace is highly adaptable, its hard-to-know characteristic is its "omnivorous" habit, which allows it to eat almost anything. This characteristic allows it to "behave" in the wild, often preying on the eggs of other fish, exacerbating the decline of native fish.
Perhaps for the sake of protecting the native ecosystem, dace is not used as food. However, unlike other invasive species, dace has soft flesh with many bones and is rated as "one of the most unpalatable fish". This makes people shy away from it, and even choose to release it after they catch it.
Due to its strong survivability and rate of reproduction, the population of dace is increasing rapidly. According to a 2019 survey, dace has surpassed tilapia in the Pearl River as one of the most dominant alien species in the region.
Therefore, in the case of the detection of alien species, especially invasive and highly reproductive species such as dace, measures should be taken in time to avoid further impacts on the local ecology.