The greater weever fish has poisonous spines

The greater weever (Trachinus draco) lives along the Norwegian coast north to Trondheimsfjorden and has poisonous spines. Getting stung by a weever fish can be very painful. The greater weever is the most poisonous fish in Norwegian waters, while the spiny dogfish (Squalus acanthias) and rabbit fish (Chimaera monstrosa), for example, release less potent poisons. Treatment after being stung by one of these fish is the same as for the greater weever. For advice and an assessment, contact the Norwegian Poison Information Centre on 22 59 13 00.

Person with hand in water. Fish with brown spots and stripes and white belly

​Greater weever (Trachinus draco)​ is a fish with poisonous spines that can cause intense pain in the wound.

Illustration: Jan Borgeraas

The greater weever (Trachinus draco) is a 30-40 cm long fish, which is a greenish-golden colour with brown-green stripes. It occurs along the coast north to Trondheimsfjorden, in Europe south to the Mediterranean and North Africa, but not in the Baltic Sea.

The poisonous spines consist of one spine on each operculum and five to eight dorsal spines. The spines of the greater weever are quite robust. It is rare for them to break off and be left behind in the wound. However, the spines are covered with a layer of skin which remain in the wound after being stung. The actual injection of the venom is triggered mechanically by pressure. If a spine and the surrounding connective tissue/glandular tissue is subjected to pressure, the venom is forced out along the spine and into the puncture channel.

Every year, many fishermen and bathers along the Norwegian coast are stung by weever fish. This normally occurs when handling the fish or when stepping on a fish that is partially buried in the sand.

Symptoms of poisoning by a weever fish

  • The venom causes intense pain in and around the puncture site. The pain can radiate outwards.
  • Swelling and reddening around the puncture site is common. The swelling can spread and become extensive. It can take a long time for the swelling to recede. Up to 10 days is not uncommon.
  • General malaise such as headache, fever, chills, nausea/vomiting, dizziness, sweating and aching joints may occur.
  • Allergic reactions can occur, but are very rare.
  • Complications and late effects may occur.

First aid following poisoning by a weever fish

  • Remove any visible residues of spines and fish skin.
  • Treatment with hot water often provides rapid pain relief. The affected part of the body should therefore be immersed in hot water (approximately 40-45°C) as soon as possible. Check the temperature by dipping an unaffected part of the body into the water (to avoid scalding).
  • Continue treatment with hot water until the pain has subsided (often within 30-45 minutes) or up to 90 minutes. Consider other pain relief if treatment with hot water is ineffective.
  • Treatment with hot water is important. If this treatment is not administered, the pain can last for many hours or even up to 24 hours or more.
  • After the end of hot water treatment, the wound should be treated and cleaned in the normal way.​
  • Consideration should be given to having a tetanus injection (applies generally to all puncture wounds).

Seek medical advice if:

  • the symptoms are severe or persistent
  • the pain persists despite heat treatment
  • your general condition deteriorates
  • the puncture wound becomes infected