State authorities in the United States are concerned that the introduction of this fish species has caused significant damage since its arrival.
Severe Damage Caused by an Invasive Fish Species
The Nevada Wildlife Department has raised an alarm about an invasive fish species that has surprised many, especially since it is quite familiar to many in Asia. Following this policy, live Nile tilapia will no longer be permitted for use in Las Vegas, Nevada. Surprisingly, Florida authorities have issued a similar announcement. According to officials from these regions, Nile tilapia, once released into local waterways, has caused considerable environmental and economic damage. Why are these states sounding the alarm over Nile tilapia?
The invasive fish species alarming the U.S. is Nile tilapia. (Photo: Pixabay)
Nile tilapia was initially introduced to the U.S. in efforts to control aquatic vegetation in fish farms and ponds. However, they later became an invasive species in several states, including Florida and Texas. They compete for food and space, and they threaten native species. Fish communities have been impacted by these invaders, leading to concerns about genetic diversity among fish species due to hybridization with other species in their genus.
Additionally, Nile tilapia reproduce at an alarming rate. Specifically, in the Muddy River system, where Nile tilapia have nearly driven a native fish species to extinction, a costly eradication program lasting five years has exceeded $600,000.
Nile tilapia is an invasive species competing for food and space with native fish. (Photo: Pixabay)
Not only does it cause environmental damage, but the ban on breeding Nile tilapia has also led to significant losses for fish trading businesses. Fresh tilapia will lose much of its value and appeal to customers. Finding an alternative fish that can be sold live may take up to a year, as it requires establishing a farm, breeding fish, and undergoing inspections before going to market, posing numerous challenges for businesses. State authorities warn that the “invasion” of Nile tilapia could cause millions of dollars in damages to the U.S. economy.
A Fearsome Invasive Fish Species
Nile tilapia (Scientific name: Oreochromis aureus) is a species of tilapia native to West Africa and the Middle East. This economically valuable species has been introduced in various locations and has developed into an invasive species.
Nile tilapia has a purplish body, glossy scales, and 9-12 dark parallel stripes running from its back to its belly. The tail fin has dark black stripes running from top to bottom, with a distribution throughout the tail fin. The dorsal fin features white spots running parallel on a gray-black background. The dorsal and tail fins have a light pink color. Nile tilapia can grow up to 0.6 meters in length and weigh 4 kg. Male tilapia grow quickly, reaching a weight of 0.4-0.6 kg within 4-5 months of breeding. There is a significant growth rate difference between males and females, with males typically growing 15-18% faster than females after 4 months.
Nile tilapia is an invasive species causing vast environmental and economic damage in the U.S. (Photo: Pixabay)
Nile tilapia can consume almost all types of natural food and organic debris in farms. They not only help eliminate small animals that carry diseases but also clean the environment and provide valuable products. When young, they primarily eat plankton (algae and small animals) (20-day-old fish measure approximately 18mm).
As they mature, they feed on organic debris along with algae settling at the bottom of ponds, eating larvae, insects, and aquatic plants. In aquaculture, they also consume processed feeds made from trash fish, crabs, shrimp, snails, dried fish meal, corn meal, cassava, sweet potatoes, wheat flour, fine bran, soybean meal, and peanut meal. In the wild, they usually feed from depths of 1-2 meters. Each year, Nile tilapia can spawn 6-11 times. Females lay about 200 eggs each time in self-made nests, after which the males fertilize the eggs. The eggs and fry are kept in the parents’ mouths for about two weeks. Males dig nests, while female tilapia incubate the eggs in their mouths. Fertilized eggs remain in the mouth until they hatch, with each spawning producing 1,000 to 2,000 eggs and multiple spawns occurring.
Nile tilapia can survive temperatures up to 42°C and cold down to 11°C. (Photo: Pixabay)
Nile tilapia are easy to raise and can survive in less than favorable environments. They can thrive in freshwater, brackish water (up to 32 parts per thousand salinity), and even lightly acidic water. While most fish are sensitive to dirty water, Nile tilapia can endure water with ammonia levels up to 2.4 mg/liter and oxygen levels as low as 1 mg/liter. They can tolerate temperatures up to 42°C and cold down to 11°C. Their pH tolerance ranges from 5-10.
Moreover, experts from James Cook University in Australia have discovered that this fish species can “walk.” They can crawl across islands in the Torres Strait for up to six days without water. This is due to the air-breathing organs found in Nile tilapia. During drier periods, they burrow into the mud to survive. Nile tilapia can move around on land using their pectoral fins, and they can even climb trees. Despite being a species that naturally thrives in freshwater, they can also survive in saltwater.
In Australia, Nile tilapia pose a threat to the country’s native fish species. They can also endanger birds, capable of choking them with their gills.
Nile tilapia can walk on land and survive without water for up to 6 days. (Photo: Pixabay)
Previously, Chinese media stirred public interest after releasing a video of a tilapia that revived after being frozen for two years at -32°C. Scientists explained that this revival is due to a type of protein called AFP – Antifreeze Protein. This protein prevents cell death when the organism is frozen. AFP attaches to ice crystals in the cells, inhibiting their growth, spreading, and crystallization, thereby protecting the cells. Meanwhile, the cytoplasm becomes denser, making it harder to freeze. This is why a tilapia can survive despite being frozen.
With such remarkable abilities, Nile tilapia have raised concerns among scientists that if proper countermeasures are not prepared, the damages that the U.S. and Australia will incur could be much more significant.
