The weever fish, a small but potent marine animal, is one of the few venomous fish found in temperate coastal waters. Classified under the genus Trachinus within the family Trachinidae, this ray-finned fish is common throughout the eastern Atlantic and Mediterranean Sea. The fish is primarily a concern for beachgoers due to its habit of inhabiting shallow, sandy areas where it can inflict a notoriously painful sting.
Identifying Characteristics and Habitat
Weever fish are relatively small, with the lesser weever (Echiichthys vipera), the species most often encountered by bathers, typically reaching a length of 10 to 15 centimeters. The fish has an elongated, tapered body and is generally a dull yellowish-brown or sandy color, providing excellent camouflage against the seabed. Its physical features, including a large, upward-angled mouth and eyes positioned high on the flat head, are perfectly adapted for its predatory lifestyle.
This species is benthic, preferring sandy or muddy bottoms in coastal regions. During the warmer summer months, the lesser weever moves into the shallow waters close to shore, increasing the risk of human encounters. The fish spends most of its time partially buried in the sand, with only its eyes and the tips of its venomous spines protruding.
The Mechanics of the Venomous Sting
The weever fish’s defensive mechanism is a sophisticated venom delivery system located on its fins and gill covers. The venom is injected through sharp, grooved spines found on the first dorsal fin and a single robust spine situated on each gill cover, or operculum. When the fish is disturbed or stepped on, the pressure causes the fine membrane covering the spines to tear, which in turn ruptures the venom glands.
The venom itself is a complex mixture of thermolabile proteins, which are sensitive to heat, and biogenous amines. One of the primary pain-inducing components is 5-hydroxytryptamine, also known as serotonin, which is responsible for the immediate and intense local pain. The venom also contains a potent protein known as Dracotoxin, a polypeptide that can exhibit neurotoxic and hemolytic properties in some organisms. This combination of toxins produces a sudden, excruciating, and radiating pain that is often described as a burning sensation and can persist for several hours, accompanied by swelling and redness at the puncture site.
Systemic symptoms, while less common, can include nausea, headache, fever, and, in rare instances, more severe reactions like hypotension.
Immediate Treatment After a Sting
Prevention is the most effective defense against a weever fish sting, which can often be achieved by wearing substantial water shoes or thick-soled sandals when wading in shallow, sandy areas. A technique known as the “weever shuffle” is also advised, which involves shuffling the feet along the seabed rather than stepping.
If a sting occurs, the most effective first aid involves the immediate application of heat to the affected area. Since the venom is protein-based and thermolabile, immersing the wound in non-scalding hot water will help to denature the protein structure of the toxin, effectively inactivating it. The water should be as hot as the person can tolerate without causing a burn, ideally between 40 and 45 degrees Celsius (104–113 degrees Fahrenheit).
The affected limb should be kept immersed for a minimum of 30 to 90 minutes, or until there is a noticeable reduction in pain. Once the pain has subsided, any visible spine fragments should be carefully removed using tweezers. Seeking medical attention is highly recommended if the pain does not diminish after the hot water treatment, or if symptoms progress to include severe swelling, breathing difficulties, or signs of an allergic reaction.