A powerful, snake-shaped fish that patrols rocky reefs and underwater crevices. The European conger is a nocturnal hunter with a fascinating life cycle and an important role in marine food webs.
Scientific name: Conger conger Marine fish Family CongridaeThe European conger (Conger conger) is a large member of the eel-like fishes. Although it resembles a snake, it is a fish: it breathes through gills, moves with fins and lives in seawater. “Sea eel” can refer to several species in everyday speech, so this guide focuses on the European conger.
Congers have long, muscular, almost cylindrical bodies, smooth-looking skin, a large head and strong jaws. The dorsal, tail and anal fins form a continuous fin fringe along much of the body. Their backs are usually grey, brown or dark grey, while the underside is paler.
Large European congers can approach three metres in length, although many are much smaller. Their flexible bodies let them turn through narrow rocky gaps, while their powerful jaws help them seize slippery prey.
A conger travels by sending waves of muscular movement down its body. This undulating motion works well in open water and helps it manoeuvre through reef crevices and around the seabed.
Like many fish that forage in dim environments, congers make use of smell and other sensory information to find food. Their sheltered, bottom-dwelling lifestyle means they do not need to chase every prey item across open water.
The European conger occurs in the eastern Atlantic, from waters around Norway and the British Isles south towards West Africa, and in the Mediterranean Sea. It is also reported in the Black Sea. Its exact distribution and depth range vary with location and life stage.
Cracks, ledges and boulder fields offer shelter from disturbance and a place to ambush prey.
Artificial structures and underwater cavities can provide the same kind of hiding places as natural reefs.
Congers live near the seabed from relatively shallow coastal water to much deeper areas offshore.
The conger is a carnivore and an opportunistic hunter. Its menu depends on the prey available in its habitat and on the size of the fish.
Congers are often most active at night or around twilight. They may leave a shelter to search the seabed, investigate crevices or seize prey that comes within reach. They are not necessarily active only at night; behaviour changes with local conditions.
The conger’s life cycle is unusual. Much of its reproduction takes place far from the rocky coastal habitats where adults are commonly seen.
As they mature, congers may move away from their usual coastal feeding grounds towards deeper water associated with spawning.
After spawning, tiny larvae drift in the water column. Their flattened, transparent, leaf-like form is very different from the shape of an adult.
As they develop, young congers change shape and eventually recruit to coastal and shelf habitats, where they grow and feed.
The full reproductive process is difficult to observe directly, and details such as exact spawning locations and timing can vary or remain uncertain. European congers are generally considered to reproduce once near the end of their lives; adults are thought to die after spawning.
By eating fish and invertebrates, congers take part in the flow of energy through rocky-reef and seabed food webs. They may also be prey for larger marine predators, especially when young or smaller.
Predators help shape the behaviour and abundance of prey species. Congers also use complex habitats such as reefs and wrecks, highlighting the value of protecting the structures that provide shelter for marine life.
The European conger is caught by commercial and recreational fisheries in parts of its range. Fishing pressure, habitat disturbance and changes in marine ecosystems can affect local populations. The conservation situation can differ between regions, so local fisheries guidance is important.
Its long shape is an adaptation for swimming and sheltering in tight spaces, not a sign that it is a reptile.
The European conger is a marine species and should not be confused with the European eel, which has a different life history.
Young eel-like fishes can pass through a transparent, leaf-shaped larval stage before taking on a more adult-like form.
Which statement about the European conger is correct?