Inhabits all types of benthic habitats from streams to shores of large rivers and lakes. Naturally found only in water bodies connected to the sea (Ref. 59043). Territorial and solitary species; 'schools' of young eels which are observed from time to time are a mass response to outward conditions and not of active assembling (Ref. 172). Amphihaline (Ref. 51442). Migrates to the depths of the Sargasso Sea to spawn (Ref. 172, 51442). Eel larvae (leptocephali) are transparent ribbon-like. They are brought to the coasts of Europe by the Gulf Stream in 7 to 11 months time (Ref. 51442) and can last for up to 3 years (Ref. 8994). They are transformed into glass eels (6-8 cm length, cylindrical in shape and transparent to slightly pigmented in colour). They enter the estuaries and colonize rivers and lakes (Ref. 11941, 51442); some individuals remain in estuaries and coastal waters to grow into adults (Ref. 88171). The glass eel stage is followed by a long feeding period (from the yellow to the silver eel stage) lasting 6-12 years in males (Ref. 6125) and 9-20 years in females (Ref. 6125). Yellow and silver eels are benthic, found under stones, buried in the mud or in crevices (Ref. 89138). Yellow eels eventually lose their pigmentation, becoming dark dorsally and silver ventrally (called silver eels). Silver eels are also characterized by a clear contrasting black lateral line and enlarged eyes (Ref. 6125). At the end of their growth period, they become sexually mature, migrate to the sea and cover great distances during their spawning migration (5,000-6,000 km); with extensive daily vertical migrations between 200 m at night and 600 m during day time, possibly for predator avoidance (Ref. 89140). Gametogenesis occurs entirely during spawning migration. Average life span is usually 15-20 years (Ref. 88171). Male eels can grow up to 50 cm TL (Ref. 39903). Occurs at temperatures ranging from 0-30°C (Ref. 172). Its food includes virtually the whole aquatic fauna (freshwater as well as marine) occurring in the eel's area, augmented with animals living out of water, e.g. worms (Ref. 172). Best temperature for making eels sexually mature is 20-25°C (Ref. 35388). Sensitive to weak magnetic fields (Ref. 89141, 89142). Their high fat content and benthic feeding habits in continental waters make them vulnerable to the bioaccumulation of pollutants, such as heavy metals and organic contaminants, that may result in organ damage and impaired migration capability (Ref. 82710) and lowered genetic variability (Ref. 82711). Review of information supports the view that the European eel population as a whole has declined in most areas, the stock is outside safe biological limits and current fisheries not sustainable (Ref. 82712). Obvious decreasing of the stocks for all the continental native distribution area (Ref. 40476). Utilized fresh, dried or salted, smoked and frozen; can be fried, boiled and baked (Ref. 9988).