Number 11: Walking Catfish This Southeast Asian evolutionary miracle
has a shocking and frankly unnerving skill. It can walk on land. Yes, “walking catfish” isn’t just
a cute moniker. These gifted creatures use their tail and fins to wriggle across the land. That, in
and of itself, means that the walking catfish has the ability and drive to travel. These incredible
fishes first hit the scene in the United States in the 1960s, when they were introduced to Floridian
waters. Since then, they’ve shown up in Nevada, Connecticut, California, Massachusetts, and
Georgia. Walking catfish are opportunists, and they have no issue pulling themselves
into stock ponds, which seriously damages and diminishes those fish populations.
Some farmers even put chicken wire around their ponds to keep walking catfish out. However,
given what we know about these extraordinary animals, it’s only a matter of time before they
figure out a way to get around that too! Number 10: Goldfish
Goldfish are among the most invasive species in the entire world, but they’re not always a
problem. In some ecosystems, goldfish get along just fine with native fish species,
but introduce them to a place with poor water quality and watch out! Goldfish aren’t tolerant
of foul water and will threaten already fragile ecosystems in these environments.
To top it off, goldfish can grow to gargantuan sizes, quickly crowding out the competition and
establishing dominance. They also breed rapidly, forming a critical mass that
can devour vast amounts of food sources and leave the other fishies high and dry!
Number 9: Veined Rapa Whelk Veined rapa whelks are beautiful creatures
native to the northwestern part of the Pacific Ocean, but they’ve packed up their bags and
infiltrated the rest of the world. These animals have a gorgeous shell and a nasty attitude,
and the badass beauties have absolutely no trouble dominating their new surroundings and swallowing
up everything in sight. In 1946, the veined rapa whelks appeared in the Black Sea, and before long,
they’d spread to the mighty Mediterranean Sea. In 1998, the creatures finally made their way across
the pond, showing up in the Chesapeake Bay. How did they get there? Some think that the veined
rapa whelk were stowaways that hitched a ride on clueless ships crossing the Atlantic. However they
arrived, veined rapa whelk are here to stay. Number 8: Green Crab
The European green crab was originally stocked up and shipped all over the globe as fishing bait,
but this crustacean had different plans for global domination. Green crabs have
exploded worldwide, establishing themselves in both Americas, Australia, South Africa, and part
of Southeast Asia. In a bizarre twist, it’s not the green crabs themselves that are being eaten;
they are doing the eating! Green crabs consume whole hosts of local animals, including mollusks,
worms, and even other crabs. Yep, green crabs are carnivorous. Their appetites also know no bounds,
and green crabs have simply decimated the commercial shellfish industry in many places
around the world, which is really, pretty much, the definition of irony.
Number 7: Asian Carp
Asian carp are colossal fish that initially hail from Eastern Russia and China,
and their introduction across the pond has caused massive headaches for plenty of people. Asian carp
were brought to the United States and Europe on purpose. Since they tend to be beautiful
additions to your average koi pond, many people imported them as pets… but we’re willing to bet
that they probably didn’t bank on the Asian carp’s size. Other Asian carp were transported as sport
fishing bait, and a small quantity most likely wound up as food, but it was the pets that were
the primary issue. As people abandoned their carp to local lakes, streams, and rivers, they
began to change their new ecosystems dramatically. Asian carp can swell up to 30 pounds. For context,
that’s as heavy as three average-sized bowling balls or a small fifth grader. They also eat
a lot, dominating local food supplies and even chowing down on fish roe. To make matters worse,
Asian carp stir up a lot of sediment when they move around, changing the water’s dynamic and
possibly making it hostile to other creatures.
Number 6: Mosquitofish There’s a good reason to love mosquitofish;
as their name suggests, they consume tons of mosquitos. On the flip side, they also can
steamroll local populations of fish, and they are unapologetically aggressive. Since mosquitos carry
all sorts of nasty diseases like Dengue Fever, Yellow Fever, and Malaria, you might initially
be on the side of the mosquitofish. After all, even though it’s pretty Machiavellian, the ends
do justify the means. But that’s only part of the story. Mother Nature has a way of self-regulating,
and in many areas, local fish will eat mosquito larvae to keep the population down.
The mosquitofish’s utter domination can upset the ecological balance, causing more mosquitos in the
long run. That’s not good for anyone! In a weird twist that fits the mosquitofish saga perfectly,
researchers have developed what they see as an ingenious way of dealing with the fishy bullies;
a robotic bass designed to scare the daylights out of the mosquitofish and stop them from breeding.
Number 5: Zebra Mussel Zebra mussels hail from the Caspian Sea,
but you’ll find plenty of them lurking in far-flung corners of the world far from their
place of origin. These bivalve mollusks are as tough as they come, flourishing equally in fresh
and brackish water, which gives them a substantial competitive advantage over other local creatures.
Zebra mussels first spread throughout Europe’s canals in the 18th and 19th centuries, eventually
reaching the Baltic Sea and taking over that too. In 1998, the first zebra mussels were spotted in
the United State’s Great Lakes, wreaking total havoc for local populations and even infiltrating
power plants and water treatment facilities. Since their introduction to the Great Lakes,
the zebra mussels have just gotten bolder, making their way into rivers and lakes all throughout
North America. The biggest problem zebra mussels pose is their huge appetite. These animals can,
and will, gobble up virtually anything leaving no food for the native fish who, let’s face it,
really were there first. Number 4: Northern Pacific Sea Star
Northern Pacific sea stars are one of Southeast Asia’s accidental exports and are now causing
big problems in Australia. The creatures are native to Korea, Japan, and China’s waters,
but they hitched a ride to Australia as secret stowaways on local boats. Now,
there’s no getting rid of them. Northern Pacific seastars are exceptionally aggressive creatures,
and they are not picky eaters at all. Their voracious appetite is only matched by their
ability to reproduce in the blink of an eye. With millions of these sea stars in Australia’s waters,
the local fish population is starting to suffer. The spotted handfish, a critically endangered
creature, is in grave danger, as are certain types of local shellfish, mollusks, crabs, sea urchins,
and even other sea stars. Talk about bad guests! Number 3: Snakehead
Snakehead fish originally come from Russia, Korea, and China, but you can rest assured that
these beasties are coming to a lake or river near you if they are not there already. Snakeheads are
apex fish, staking their place firmly at the top of the food chain, which means that any local fish
that come at them will lose badly. No natural predators and an assassin’s taste for blood
make snakehead fish formidable foes that can easily muscle out local fish populations for food
if the snakeheads aren’t eating them, that is! Did we mention that these gnarly fish can breathe
air? Some varieties of snakehead fish can live out of water for 4 full days,
as long as they are in a wet or heavily damp area. Snakeheads eat everything. They love
fish, insects, frogs, and crustaceans alike. They are not picky! These fish are so destructive that,
as of 2002, it’s now illegal to purchase or own a snakehead fish in the United States.
Number 2: Nile Perch Ethiopia's native Nile perch has
devastated the rest of the continent, specifically East Africa after it was accidentally introduced
to new waters in 1962. Tanzania’s Lake Victoria’s been ravaged by the Nile perch. These creatures
shove their way in, consuming everything in their path, including other fish, and have been directly
related to the extinction of 200 species of native fish. Who knows how many more are teetering on the
very brink of extinction, thanks to the Nile perch? Additionally, these fish reproduce at
incredible rates. One lone fish can generate up to 15 million eggs at one time, so other species
simply don’t have a snowball’s chance in hell of catching up. Once the Nile perch take over,
other fish are crowded out, drastically changing the ecological makeup of any body of water.
Number 1: Lionfish
Venomous, cranky, dominant lionfish pose a major threat to local fish in the Western Atlantic.
These fish are initially from the Indo-Pacific and Red Sea areas,
but two separate strains of the toxic bullies have made their way across the ocean,
and that’s not good news at all. Lionfish are aggressively invasive, and they can be very
dangerous to humans, as well as local fish. Two key elements make up the lionfish perfect storm;
an untamable appetite and long venomous fins full of a devastating neurotoxin.
Lionfish have few, if any, predators, so they can quickly establish control over their new region
and start wreaking havoc. They are especially dangerous to local reef creatures, and the
problem is so bad that diving teams are regularly sent out in places like Florida to collect them.
Thanks for watching! Would you
rather wrestle with an ill-tempered snakehead fish or swim in a pond full of 30-pound Asian carp?
Let us know in the comments section below.