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Introducing The Walking Catfish

August 10, 2013

Walking Catfish

Let us begin a discussion about the Walking Catfish with a little limerick:

There once was a catfish walking

That had the folks in Florida talking.

The fish walked the roads,

Got splattered like toads.

And the carcasses got drivers to balking.

What sane motorist would not balk at the prospect of swarms of catfish jaywalking across the street? And what sane pedestrian would, the next day, not become squeamish at the sight of those perambulating catfish that never made it to the other side of the road – i.e., were the victims of tire-tread? Then again, what sane person would live in Florida in the first place? But that’s another story.

Where did these freakish critters come from? In March of 1967, a fisherman caught a new type of fish, one that looked like a catfish yet acted like Mr. Easy. Scientists identified it as Clarias batrachus, or, in the vernacular, the Walking Catfish. It is a species indigenous to southeastern Asia. It turned out that Floridians had been buying them to put in their aquariums, except that someone – we’ll call him the owner of Penagra Aquariums, which is west of Deerfield Beach — thought it an even cooler idea to put his allotment in a pond at his facility. This was like putting the Birdman of Alcatraz in a holding cell and leaving the door open. The fish walked away and were soon in neighboring ponds and using drainage ditches as avenues to even murkier pastures. They became so abundant that, in 1974, a former Curator for the New York Zoological Society named Edward Ricciuti, wrote a children’s book about the plague.

The book is called Donald and the Fish that Walked. The main character, Donald, is a boy living in South Florida. One day he hears his dog barking at…a walking catfish. The fish is pink, with “bright eyes” that are “like hard, shiny stones.” He follows the fish until it jumps into a water ditch, and duly pronounces the event “Creepy.” He tells his parents that he saw a walking catfish, and they, in turn, pronounce him nuts. Donald’s friends echo the sentiment, claiming that they had seen “flying alligators.” Ha ha. Then his dad reads in the paper that “strange new fish are living here in South Florida. They are catfish that can walk.” Sorry, son, we were ready to commit you to the loony bin.

Now Donald and his posse run into Mr. Walter, the book’s scientific voice, who is in the process of catching a Walking Catfish in his net. He tells the boys that, yes, Carias batrachus is now all over the ‘hood, and, worse, the species is a true pest, and “We want to get rid of them. They don’t belong around here.” They are from Asia. Certain Floridians brought them here “for their fish pools. But the catfish got away” by walking from one pond to another. They are able to do this because they can breathe air and pull themselves along on their two front fins, allowing them to be proverbial fish out of water, only one that also lays an obscene amount of eggs. They are total gluttons who are eating all the available aquatic food, and thus crowding out all the other fish in the ponds. This is the definition of an invasive species. Mr. Walter states the obvious, that if “this keeps up only the catfish will be left.”

Donald now becomes the voice of biodiversity, saying: “I guess it is better to have lots of fish. Not just one kind.” The only way that these fiendish critters can be stopped from taking over the whole state is the arrival of a massive cold front, something that never happens in their place of origin, southeastern Asia. That night Donald and his dad are driving when they come upon a swarm of catfish trying to get to the other side of the road. Creepy indeed! A long time later, South Florida experiences one of its rare cold spells. Donald sees Mr. Walter scooping out a bunch of dead catfish. The kid asks if this is the end of the Walking Catfish invasion, to which the scientist answers that it could very well be unless Carias batrachus adapts to the cold. The book ends with Donald catching a glimpse, out of the corner of his eye, of a pink thing with bright shining eyes “sliding down the side of the ditch.” They’re baaack!

The official line on the Walking Catfish in this country as listed in the National Audubon Society Field Guide to Fishes is: Class: Osteichthyes, Order: Siluriformes, Family: Clariidae, Genus: Carias, Species: batrachus. It grows up to 14 inches; is usually colored “dark brown to olive above; lighter below.” Some populations are albino, white to pinkish, the latter type being the one that was stalking Donald. It has four pairs of barbels, which are the whisker-like projections from the lips that are responsible for putting the “cat” in “catfish.” Its habitat is “lakes, swamps and sluggish canals with debris and aquatic vegetation over mud.”

The Audubon folks omit a lot of details. Clarias batrachus comes from eastern India and Southeastern Asia, which are hot and moist environments. The Walking Catfish does not so much walk as slither, using its pectoral fins, which have very strong spines, as props, much like how a human will use crutches as more aid than actual legs. It has the ability to thrive in hypoxic waters, an aquatic environment with a deficient supply of oxygen. This is due to an auxiliary breathing organ, what Britannica describes as “a modified gill arch that forms an air chamber,” that allows the organism to survive in open air. It is believed that this was an evolutionary adaptation that gave the Family Clariidae an advantage over other fish in oxygen-poor brackish and swampy waters. They are benthic omnivores – i.e., they will eat anything, even if it has to scour the very muck and mire at the bottom of any body of water. Their open menu includes “eggs of other fishes, small fishes…annelids, crustaceans and insects.” When they have depleted all the nutrients in a given pond, it is onto the next, unsuspecting pond, utilizing their stiff pectoral fins and special breathing organ that allows them to survive up to twelve hours on the open road, always leaving in their wake a biological apocalypse.

If the fictional young Donald were now a fifty-five-year-old adult still living in South Florida, he would be the dad swerving on the road trying to mash these strolling catfish. Carias batruchus has expanded all over South Florida and half way up the peninsula to the latitude where periodic cold temperatures halt any further northern migration. In 1970, the temperature in Miami dropped to 29 degrees Fahrenheit, the event mentioned in Donald’s tale. This killed off a large percentage of this invasive species. But their survival skills are legendary, as many of them stayed low in warmer waters, or burrowed into mud banks, and waited out the cold. True they are gluttons, but they can also go without food for up to eight months. Then there is their other claim to fame, a reproductive prowess of rabbitian proportions. Thus, once the weather returned to normal, the survivors resumed spawning until they were again outnumbering and besieging, en masse, their less stalwart aquatic neighbors.

The indirect effect on humans from such depredation on biodiversity is felt through the resulting ecological and economic harm. Any environment that comes to be dominated by one species loses its elasticity. Thus it can collapse in an instant without the multitude of safeguards inherent in a diverse animal community, much like how a roof will have a better chance of not collapsing if there are scores of supporting vertical beams rather than one large beam. One does not have to be a Greenpeace member not to appreciate that a healthy environment is better to live in than an unhealthy one.

The economic harm to humans comes in the loss of revenue gained from the harvesting of other species, other fish. Then there is the money involved in recreational fishing, what with rods, reels, wading boots and bait. The Walking Catfish has been observed to kill large bass for mere sport, not for consumption. Even the most die-hard fisherman will tire of casting for only slimy walking catfish.

There are dissenters to the walking-catfish-as-antichrist school of thought. One is Jeffrey Hill, a doctoral candidate at the University of Florida. He writes that not only are Walking Catfish doing no harm, but neither are the other 104 exotic fish species that have been found in the Sunshine State. In fact, he says, these invasive species increase diversity, rather than the other way around. “No native fish has become extinct in Florida due to the introduction of exotic fish.” In other words, 104 fish added to the original count is more, not less, total fish. Mr. Hill seems to be in the minority, or perhaps just stirring up controversy to get that doctorate. The Gulf States Marine Fisheries Commission says, straight-up, that the Walking Catfish “remains one of the most notorious and harmful non-indigenous species in the Gulf of Mexico ecosystem.”

Walking Catfish can have a direct impact on humans. The one already mentioned is the mess they cause from time to time on the Florida roadways. They usually travel on wet, rainy nights, being that, one, they are nocturnal, and, two, the moisture protects them from desiccation. The aesthetics of such a sight is bad enough, but trying to drive on a road made slick by splattered catfish can be downright dangerous. There are occasions when Route 41 (Tamiami Trail) is declared hazardous due to a host of catfish that could not quite make it to the other side of the road.

Another instance, and one that has a ring of poetic justice, is that Carias batrachus will invade commercial aquaculture facilities, the same ones that brought the species to Florida in the first place, and devour the resident fish. This is a direct hit to the economic animal, man – and a true case of the chickens coming home to roost, except these chickens are slimy with “bright eyes like hard shiny stones.”

What has been done to turn back the tide against this creepy invasion? The answer is a mixture of federal legislation and the state of Florida crossing its collective fingers. The federal government has declared the entire family Clariidae, which means all “air-breathing catfishes,” as a bad species and one illegal to purchase or own without a permit. The finger-crossing part of the equation comes in hoping that cold weather will arrive more often to keep these pests under control, as there is little hope left of them ever being exterminated on a permanent basis. Remember that Walking Catfish can survive in the unhealthiest of waters. As such, anything that can kill this mutant beast will also kill everything else, maybe even humans.  Therefore, the Walking Catfish is here to stay in Southern Florida. Donald must be telling his own children to just get used to those catfish and be careful driving on wet rainy nights when they go for their group walks.

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  1. …An old favorite

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