Acording to the IUCN, " An alien invasive species is a species intorduced outside its natural past or present distribution, if this species becomes problematic, it is termed aas an invasive alien species.
The following are our top five most invasive alien fish species around the world.
First off , terrorizing central Asia, Europe, Japan and the USA we have the Northern Snakehead. This fish is to Northern Africa and Asia. It was most probably introduced through people who have bought these fish through local aquarium owners that no longer wanted them. Now these fish are highly threatening to other local fish populations.
Zooplankton, larvae, and small fish are threatened by the young whereas larger fish, amphibians, reptiles and some birds are threatened by the adults.
These fish can breath air and live out of water for up tow four days if kept wet.
These fish have long narrow bodies with a large jaw and canine like teeth. There irregular shaped body gives their head a shape like appearance and thus their name. The snake head can grow up to 4 ft in length and are oftentimes confused with barbut.
Since 2002, it has been illegal to keep a Northern Snake Head in the United States. If one ever caught one of these fish it is recommended that they kill it immediately. In some lakes they have used chemicals to kill off the Snake Head however this can be dangerous and kill non-target fish species. So far the species hasn’t completely managed to overthrow other fish populations. If this happens, it would result in millions of dollars to eradicate them.
Our second menace to the United States is the Walking Catfish. This fish is native to Asia and was introduced in the 1960's by aquaculture farmers. After this, they spread like wildfire and were made illegal to possess by 1967.
Walking catfish are resilient fish and have two adaptations which makes it easier for them to survive and thrive. 1) This fish can breath air and 2) It is able to waddle on land using its specially designed fins. Its ability to survive in stagnant water makes it valuable in Asia, allows it to thrive in the United States and makes them more dangerous as an invasive species.
This fish is notorious for attacking fish farms and causes millions of dollars of damage each year to the farmers. These fish carry a disease dangerous to other catfish and therefore infect the farmed fish. Farmers fight these fish by erecting fences to keep these fish out. The Walking Catfish is highly sensitive to the cold which has stopped their migration North.
These fish can be popular aquarium pets. Nowadays to own one requires a federal permit. The United States have classified this fish as injurious wildlife and illegal to possess. It is hard to kill since it can easily leave poisoning watering holes by walking. Many other countries have declared this fish illegal and for good reason!
The largest invasive fish on our list is the Nile Perch. Native to Congo, Senegal and Chad, this fish has substantial economic and food importance to the locals of the region.
In the 1950’s it was introduced to Lake Victoria. Initially, it brought an economic boom. However, this was at the cost of a near extinction of the native cichlids. Their introduction is one of the most cited examples of the negative effects cause by alien fish species.
Nile Perch also go by the name Goliath Perch and African Barramundi. The Nile Perch is a massive fish that can grow up to 7 feet long and 230 lbs.
No official prevention methods are being taken to reduce this invasive species population. Currently the only prevention method is commercial fishing. Fortunately, the fishing incentives (profitability) related to Nile Perch have helped lower their population.
Now, scientists have been observing the return of cichlids and other species that were almost wiped out by the Nile Perch.
The Mozambique Tilapia is native to Southeastern Africa. In 1952 it was introduced to India. Since then, it is now a dominant fish fauna. The Tilapia are so abundant that they are used as cheap crocodile bait.
Overtime this fish has migrated to many different biodiverse hot spots in the area. The problem is that other species in these areas have evolved under isolation and are not equipped to battle a new predator like the tilapia. Tilapia have also invaded Southeast Asia and the Americas. In Cuba it represents 100 % of the catch landings of fresh water species.
Tilapia resemble a bluegil and our mainly found in rivers and lagoons. Although they are vegetarians, they do not hesitate in consuming eggs and other small fish.
Many governments use poisons , screens and filters to control these pest fish. However, there is no single best way to control them. Since these fish can completely alter an ecosystem it is important to control their population and not to help spread there numbers.
The last most annoyingly alien invasive fish species on our list is the Lion A very beautiful fish, the Lion Fish has been mainly transported due to aquarists, It was first detected in the mid 1980's off the coast of Florida after previously being native to the Indo- Pacific.
Not only is it harmful to other fish species, the Lion Fish is devastating to coral reefs. This fish primarily feed on herbivores. These herbivores eat algae. Algae growth left unchecked is harmful to coral reefs therefore herbivores are imperative for their survival. The presence of Lion Fish severely destabilize this dynamic.
It is said that one Lion Fish residing in a coral reef can reduce recruitment of native fish by 79 percent.
Many Lion Fish are now hunted by spear fisherman. This has done a good job of controlling their population amongst popular dive sites. However, these fish can go very deep and are most dangerous to the reefs deep down in depth.
Currently, people are using traps to try and solve this problem. Others are promoting this fish as a delicacy to encouraging hunting. Ultimately, this fish is a danger a danger and if we want to save our marine life this is one invasive species that we need to control.