|The Range of the European conger|
Description and behavior
European congers have an average adult length of 1.5 m (4 ft 11 in), a maximum known length of around 6 m (19 ft 8 in), and maximum weight of roughly 110 kg (240 lb), making them the largest eels in the world by weight. They can be rivaled or marginally exceeded in length by the largest species of moray eel but these tend to be slenderer and thus weigh less than the larger congers. Average specimens caught will weigh only 2.5 to 25 kg (5.5 to 55.1 lb). Females, with an average length at sexual maturity of 2 m (6 ft 7 in), are much larger than males, with an average length at sexual maturity of 1.2 m (3 ft 11 in).
The body is very long, anguilliform, without scales. The colour is usually grey, but can also be blackish. The belly is white. A row of small white spots is aligned along the lateral line. The head is almost conical, and slightly depressed. The snout is rounded and prominent, with lateral olfactory holes. The large gill openings are in the lateral position. The conical teeth are arranged in rows on the jaws. The dorsal and anal fins are confluent with caudal fin. Pectoral fins are present, while ventral fins are absent.
Conger eels have habits similar to moray eels. They usually live amongst rocks in holes, or "eel pits", sometimes in one hole together with moray eels. They come out from their holes at night to hunt. These nocturnal predators mainly feed on fish, cephalopods, and crustaceans, although they are thought to scavenge on dead and rotting fish, as well as actively hunt live fish. Congers can be aggressive to humans, and large specimens can pose a danger to divers. 
This species can be found in the eastern Atlantic from Norway and Iceland to Senegal, and also in the Mediterranean and Black Sea at 0–500 m of depth, although they may reach depths of 3600 m during their migrations. It is sometimes seen in very shallow water by the shore, but can also go down to 1,170 m (3,840 ft). It is usually present on rough, rocky, broken ground, close to the coast when young, moving to deeper waters when adult.
Migration and reproduction
When conger eels are between 5 and 15 years old, their bodies undergo a transformation, with the reproductive organs of both males and females increasing in size and the skeleton reducing in mass and the teeth falling out. Female conger eels appear to increase in weight and size more than the males. Conger eels then make migrations to spawning areas in the Mediterranean and the Atlantic, "although the existence of one or multiple spawning grounds for the species remains uncertain". The female conger eels produce several million eggs. Once hatched, the larval conger eels begin to swim back to shallower waters, where they live until they reach maturity. They then migrate to repeat the cycle.
- NatureServe (2013). "Conger conger". IUCN Red List of Threatened Species. IUCN. 2013. Retrieved 15 December 2014.old-form url
- "Conger conger". EOL Encyclopedia of Life. Retrieved 11 May 2014.
- LOH, K., Hussein, M. A. S., Chong, V. C., & Sasekumar, A. (2015). Notes on the Moray Eels (Anguilliformes: Muraenidae) of Malaysia with Two New Records. Sains Malaysiana, 44(1), 41-47.
- Charton, B., & Tietjen, J. (2009). The Facts on File dictionary of marine science. Infobase Publishing.
- Shapley, R., & Gordon, J. (1980). The visual sensitivity of the retina of the conger eel. Proceedings of the Royal Society of London. Series B. Biological Sciences, 209(1175), 317-330.
- Matić-Skoko, S., Ferri, J., Tutman, P., Skaramuca, D., Đikić, D., Lisičić, D., ... & Skaramuca, B. (2012). The age, growth and feeding habits of the European conger eel, Conger conger (L.) in the Adriatic Sea. Marine Biology Research, 8(10), 1012-1018.
- "Conger Eel". BritishSeaFishing.co.uk. Retrieved 9 May 2014.
- "Conger conger". WoRMS - World Register of Marine Species. Retrieved 12 May 2014.
- "Conger Eel". UK-Fish.info. Retrieved 12 May 2014.
- "Article - Conger Eel". Galway Atlantaquaria. Archived from the original on 25 May 2015. Retrieved 9 May 2014.
- Correia, Alberto; et al. (24 April 2012). "Population structure and connectivity of the European conger eel (Conger conger) across the north-eastern Atlantic and western Mediterranean: integrating molecular and otolith elemental approaches". Marine Biology. 159: 1509–1525. doi:10.1007/s00227-012-1936-3.
- "Conger Eel - Conger conger". Marlin.ac.uk. Retrieved 9 May 2014.
- Media related to Conger conger at Wikimedia Commons
- Data related to European conger at Wikispecies
- Photos of European conger on Sealife Collection