Found all across the globe, catfish species are so diverse and numerous that they belong to their own order, Siluriformes. Most of these ray-finned species reside in freshwater bodies, and many are commercially important as food or aquarium fish. They are known for their whisker-like barbels and flattened skulls, which enhance their feeding capabilities in the benthic reaches of the water column.
As they are scaleless, catfish have evolved to respire through their skin. In some families, the skin is coated with dermal plates that serve as some form of body armor. To an extent, this may afford catfish defensive protection, but it doesn’t allow them to take an offensive stance against potential threats. Some species have an impressive number of conical or villiform teeth, which are arranged in bands throughout their oral cavities. These generally function as scrapers rather than weapons for attack.
So what does make catfish dangerous? Among the vertebrate orders, Siluriformes contains the highest number of venomous species because around half of them possess venomous spines! The next time you go on an angling trip or attempt to handle these seemingly harmless fish, take extra caution. Most of the species that we’re largely familiar with as food have non-lethal stings, but there is always the risk of injury.
Venomous Spines in Catfish
Catfish have sharp spines on the edges of their pectoral and dorsal fins. These can cause mechanical injury to handlers, resulting in inflammation, possible infection, and severe pain. While these spines are non-venomous in some catfish, there are more than 1,600 species that do possess venom glands. Toxicology studies have shown that the proteins produced by these glands tend to have hemolytic properties, though the actual chemical composition differs across taxa.
When catfish are disturbed, they tend to lock the position of their fins so that the sharp spines stick in an outward direction. As they are stiff, they are all the more likely to cause injury when touched from the wrong angle! Upon contact, the stinging proteins are delivered into the resulting wound. These are produced by glands in the epidermal layer that surrounds each spine.
When the leading edge enters or simply grazes the skin of the victim, the integument surrounding the venomous cells becomes damaged. Thus, the venom is released directly into the skin. The entire spine may even get lodged into flesh and become a foreign embedment that causes arterial and nerve damage.
While the initial symptoms of pain and swelling may be manageable without professional help, there is a danger of secondary infection from contact with bacteria or fungi. Moreover, some species have a venom composition that can even cause tissue necrosis! As the hand is oftentimes the site of injury, any infections or lingering pain must be treated right away to avoid complications. In the worst case, abscesses may even lead to the loss of fingers or a hand.
Dangerous Species to Avoid Handling
As there are so many venomous catfish species, you are not advised to touch or handle them unless you have received proper training beforehand. Those listed below have been associated with serious injuries, with some leading to fatalities. Keep in mind that dangers aren’t simply restricted to these species, but are the results of mishandling any type of catfish in general.
1) Channel catfish (Ictalurus punctatus)
The channel catfish is one of the common freshwater fish species in the US. They are often caught by anglers for sport or as food. Their stings are usually quite harmless, but they do possess proteins that may cause adverse reactions in healthy individuals.
A fishmonger who worked at a supermarket in 2013 was the unhappy victim of a live channel catfish. The fish’s spine pricked his thumb, causing severe pain. Over the course of a few days, the pain exacerbated and was further complicated by secondary infections. It took a full course of antibiotics to reduce the abscess and normalize his blood test levels.
2) Asian stinging catfish (Heteropneustes fossilis)
This omnivorous catfish is commercially farmed throughout its native range. It is often kept in personal aquariums as its dark coloration may look attractive in a brightly lit tank. It can tolerate a wide range of natural conditions and can persist in muddy and brackish waters. Interestingly, there is high demand for H. fossilis in India due to its medicinal and nutritional value.
In 2005, an aquarist who was cleaning a tank that housed a stinging catfish was actively stung on the hand. The wound had to be irrigated, debrided, and treated with local anesthesia. A combination of tetanus shots and a full course of antibiotics were then required to combat the venomous effects and hasten the healing process. This case highlights the need for prohibitions and safety measures concerning the personal cultivation of venomous animals. There are many other cases of envenomations, resulting in systemic symptoms, due to this species.
3) Striped eel catfish (Plotosus lineatus)
An invasive species with a knack for surviving in almost any type of aquatic environment, the striped eel catfish has made its way into Mediterranean waters. As catfish, these species are relatively small, reaching a maximum length of just 13 inches (32 cm). The attractively striped juveniles usually travel in schools of about 100 fish, whereas adults tend to be solitary or maintain very small groups.
Though tiny, these fish have highly venomous spines. Injuries due to contact with a spine can result in severe pain. The venom is comprised of toxic proteins that are associated with lytic, hemolytic, and edematous symptoms. In the Southeastern Mediterranean, many unsuspecting fishers have been injured by this fish while handling their fishing nets or wading in the water. Their symptoms included swelling and erythema at the site of the puncture wound. A few cases resulted in systemic symptoms such as tachycardia, chills, vomiting, and hypertension.
A Fatal Case
Knowing that a single catfish has at least 3 sharp spines, it’s no mystery why a man was killed carrying a handful of them. In 2008, a Brazilian fisherman died due to a fatal heart perforation caused by a catfish spine. Prior to his death, he had held a net full of catfish (species unknown) close to his chest. Ill symptoms were practically instantaneous once the spine became lodged into his skin. Onlookers saw the fisherman fall into the water and attempted to rescue him. After a few minutes, he had passed away.
The catfish spine was excised from the victim’s body. The autopsy report indicated that it had punctured the left ventricle. This was the first-ever case of a fatality due to myocardial perforation of a catfish spine. This instance is comparable to fatalities due to stingray spines (e.g. the Steve Irwin case). Though the spine of a catfish is small in comparison, it turns out that it can be just as lethal!
The Dangers of Electric Catfish (Malapteruridae)
There are about 20 species of electric catfish. Native to Africa, these “shocking” fish are equipped with an electric organ that can generate a shock of up to 400 volts! It is undoubtedly an evolutionary advantage, but it may have been at the cost of venomous spines. Unlike those of the majority of catfish species, the fins of the electric catfish are not a cause for worry. They also completely lack any vestige of dorsal fins.
To catch their food, Malapteruridae species make use of their electrogenic organs to incapacitate potential prey items. These include smaller fish and invertebrates that are found within or close to the benthos. They aren’t known for being particularly dangerous to people, but the largest of their kind (up to 3 feet long) can generate an electrical discharge capable of stunning a human adult.
Historically, Egyptians made use of this catfish’ special trait to treat arthritis. The mild shocks must have caused the pain to abate temporarily. Nowadays, smaller individuals are sometimes kept as novelty, ornamental fish in aquariums. They definitely cannot be housed with any other organisms, however.
Goonch, a Giant Catfish That Attacks Humans
Bagarius yarrelli, commonly known as the giant devil catfish or goonch, is an Indian species that grows to a truly massive adult size. Some of the largest individuals ever recorded reached lengths of up to 2 meters. Unsurprisingly, this fish is associated with fatal attacks. In 1998, a male teenager swimming in the Kali River was pulled underwater by an unseen creature. The boy’s remains were never found, even after a thorough multi-day search over a considerable range.
Several months to years later, two more humans disappeared into the river by being dragged into the water. One of these fatal cases occurred in 2007, when the likely culprit was first described as a “water pig”. These events drew in Jeremy Wade, the famous British biologist and television presenter of River Monsters (a documentary program that streamed on Animal Planet).
After a thorough investigation into the potential “monster” behind the disappearances, Wade concluded that the culprit was most likely a human-sized goonch. He managed to capture a 73 kg goonch that measured at exactly 2 meters! Many other large specimens were also spotted during his brief expedition.
The Final Verdict
While harmless experiences with catfish far outnumber the instances of serious injury, it pays to be aware of the dangers associated with handling them. Many fishermen, fishmongers, aquarists, and anglers continue to handle these fish with their bare hands, risking the possibility of getting stung by their spines.
Sure, a venomous sting on the hand may not be lethal, but it certainly causes a string of nasty symptoms. It’s important to educate oneself on how to hold catfish in a manner that keeps them fairly calm and reduces chances of personal injury. As for the goonch, there’s really not much to do apart from keeping clear of murky waters!
