Distribution

1. Fresh, brackish and sea water
2. Tropical to temperate seas
3. Fresh, brackish and sea water in warm and temperate zones 
4. Tropical to temperate seas

Biology

Eel-like fishes can be distinguished from most other fish due to their elongated, snake-like body. There are no ventral fins, and the dorsal, tail and anal fins are usually fused to form a single fin. Freshwater eels (Anguillidae) spend the great majority of their lives in fresh water, but migrate to the ocean to reproduce. Moray, Conger and Snake eels mostly live in coastal waters, on rocky coasts or in coral reefs.

Heat-labile toxins are present in the blood. Practically nothing is known about these toxins.

Fig. 4.9  Anguilla rostrata

Risk

Poisoning is extremely rare and there are no reports from more recent times. The toxins are inactivated by boiling or frying as well as by the gastric juices. There is a theoretical risk only if the animals were to be eaten raw or had not been cooked long enough. Moray, Conger and Snake eels are also potentially ciguatoxic.

Signs and symptoms

According to Halstead (2001a), drinking fresh, uncooked blood causes the following signs and symptoms: diarrhoea, bloody stools, nausea, vomiting, hypersalivation, skin eruptions, cyanosis, apathy, irregular pulse, weakness, paraesthesias, paralysis, respiratory distress and possibly death.

Ocular contact is said to invoke a severe burning sensation and redness of the conjunctivae, lacrimation and swelling of the eyelids.

Treatment

Symptomatic, see also ciguatera poisoning.

Literature (biological)

Halstead 1988, 2001a, Auerbach and Halstead 1989, Bagnis et al. 1970