[9][10][11] Eels tend to range from 0–700 metres (0–2,297 ft) underwater and after spawning in the Sargasso Sea, disperse North throughout the Atlantic Ocean, its coasts, and the rivers that empty into it.

[12] Feeding occurs mainly at night, via scent and prey consists of worms, fish (including ones too big to eat without biting off chunks), mollusks such as slugs, crustaceans such as crayfish, and plankton on occasion when available in large quantities.

[15] The TRAFFIC program is introducing traceability and legality systems throughout trade change to control and reverse the decline of the species.

In 1997, Innovatie Netwerk in the Netherlands initiated a project where they attempted to get European eels to breed in captivity by simulating the 6,500 km (4,000 mi) journey from Europe to the Sargasso Sea with a swimming machine for the fish.

Through a combination of fresh and salt water, as well as hormones, they were able to breed it in captivity in 2006 and make the larvae survive for 4.5 days after hatching.

[24] By 2007, DTU Aqua scientists were able to set a new record where the larvae survived for 12 days by feeding the mother eel with a special arginine-enriched diet.

[26] Deep water sampling of the presumed habitat of larval European eel in the Sargasso Sea was performed by the Galathea 3 expedition in 2006–07, in the hope of revealing the likely feeding preference at the early stage.

[33] When approaching the European coast, the larvae metamorphose into a transparent larval stage called "glass eel", enter estuaries, and many start migrating upstream.

After 5–20 years in fresh or brackish water, the eels become sexually mature, their eyes grow larger, their flanks become silver, and their bellies white in color.

Silvering is important in an eel's development because it allows for increased levels of the steroid hormone cortisol, which is needed for their migration from fresh water back to the sea.

[35] Also playing a key role in silvering is the production of the steroid 11-Ketotestosterone (11-KT), which prepares the eel for structural changes to the skin to endure the migration from fresh water to saltwater.

[40] A range of 23°C to 28°C is optimal for growth and protein based pellets and pastes are utilized as food sources for the eels after an initial few days of cod roe for the small glass ones.

[40] Diseases can be spread rapidly in the highly populated environments of fisheries if quarantine measures are not taken immediately upon arrival of new eels.

[44] Salt solutions also can treat fungal infections that cause swelling of gills and brown or white skin patches.

[46] Eel aquaculture is most prominent in Japan, yet China, Scandinavia, Europe, Australia, Morocco, and Taiwan also participate in this practice.