Alarm: Cleaner fish with fins sharper than thorns spreading rapidly in the wild

Buried fins do not decompose, puncture car tires

Having worked as a trader specializing in purchasing seafood for households in the area for decades, Mr. Pham Xuan Truong, in Hamlet 1, Vu Doai Commune, Vu Thu District (Thai Binh), has never seen so many tank cleaner fish appearing in ponds, lakes, and rivers in the area.

Cleaner fish mixed with other aquatic species in a fisherman's net.

“A few years ago, a net might only yield a few fish, but now there are countless. In some ponds, 300 kg of fish are caught, and 100 kg are scavenger fish. Many native aquatic species in the ponds are no longer there,” said Mr. Truong.

According to Mr. Truong, the characteristic of this fish species is extremely sharp fins, “sharp and hard as nails; destroying them by burying them is ineffective, they can even puncture car tires, there are some fish that are as big as a kilogram, no different from monsters” - Mr. Truong affirmed firmly. In addition, they can eat all the “color” of the pond, making other fish species… no longer have a place to live.

Because it is difficult to destroy, Mr. Truong said that most households, after collecting fish to clean their tanks, dump them into the river. This carelessness makes this fish species reproduce more and more.

New alien threat

Master Vu Thi Hong Nguyen, an officer at the Center for Biodiversity and Aquatic Resources Research (Aquaculture Research Institute I) affirmed that tank cleaner fish are a new foreign threat, after many foreign species have had negative impacts on agricultural production in our country.

This alien species poses a threat to other native aquatic species.

Called tank cleaner fish or glass cleaner fish because this species eats omnivorous food (waste from other fish, algae on the tank walls...), many experts are concerned that importing this type of fish in Vietnam will cause ecological imbalance because after being released into the environment, they easily adapt to the river environment.

Cleaner fish can approach other fish to suck the mucus, reducing the ability of other fish to grow. If other fish have poor adaptability, they will die. More dangerously, because the fish adapt strongly, they overwhelm native organisms, creating ecological imbalance. After a period of spreading into the wild, cleaner fish are now becoming a species that is at risk of harming other fish species in the same habitat.

“We conducted a survey in 14 provinces and cities across the country, from Cao Bang, Phu Tho, Yen Bai, Nam Dinh, Nghe An to Lam Dong, An Giang, Dong Thap, etc. The reality made everyone startled by the rapid spread of the aquarium cleaner fish,” said Ms. Nguyen.

According to Ms. Nguyen, compared to the northern provinces, the reproduction rate of tank cleaners in the Mekong Delta is much faster. People reported that there were nets with up to 50% of tank cleaners. These fish can easily tear the nets, but can also destroy the embankment because their nature is to eat algae and impurities in the water environment.

Regarding the harmful effects of this fish, Ms. Nguyen said that they will reduce biodiversity and aquatic resources. "In fact, through surveys, we found that in places where there are many tank cleaner fish, there is a lack of native aquatic species. Another dangerous thing is that the vitality of this species is very strong, destroying it is very difficult, while people's awareness is not high, when they catch them, they release them into the natural environment" - Ms. Nguyen said.

Answering the question about the nutritional value of this species, Ms. Nguyen affirmed: "Very low and so far very few people dare to use it as a food."

“In the proposed report, we also recommended that relevant agencies and localities take strong measures to prevent the development of this alien species. If there is no timely action now, the danger will be unpredictable,” Ms. Nguyen affirmed.

Aquarium cleaner fish, also known as glass cleaner fish or punctatus fish (scientific name Hypostomus punctatus) is a freshwater fish originating from South America, living mainly at the bottom of freshwater and brackish water bodies. The main food is algae, algae clinging to the surface of plants or the bottom. This is an omnivorous species, competing for food with other species, reproducing quickly when spreading out into natural water bodies. The fish can reproduce all year round, the survival rate of young fish is about 70% and can live without food for 1 month. Fish are imported to Vietnam mainly from Hong Kong and Singapore as ornamental fish.