General Overview
The Anguillidae family consists of the freshwater eels, a group of elongated, migratory fish best known for their remarkable life cycles. Members of this family spend most of their lives in freshwater or brackish rivers, lakes, and streams, but migrate to the open ocean to spawn, often traveling thousands of kilometers. Their young, known as leptocephalus larvae, drift in ocean currents before transforming and migrating inland. Famous representatives include the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata).
Appearance
Freshwater eels have smooth, elongated, snake-like bodies, covered in slimy skin with very small, embedded scales. Their dorsal, caudal, and anal fins are continuous, forming a single long fin fringe. Colors vary by species and age but are generally shades of brown, green, or olive with pale undersides. Many eels develop silvery coloration and enlarged eyes before migrating to the sea.
Diet
Anguillids are carnivorous. Their diet typically includes:
They are opportunistic feeders and forage mostly at night, locating prey through keen senses of smell and touch.
Habitat
Freshwater eels inhabit:
- Rivers
- Lakes
- Streams
- Wetlands
- Estuaries
They often spend several years (or even decades) in these freshwater environments. After maturation, they undergo physiological changes and migrate back to the open ocean, often to deep-sea spawning grounds such as the Sargasso Sea for certain species.
Behavior
Anguillids are secretive and mostly nocturnal, spending much of the day hidden in mud, vegetation, or under submerged debris. They are famous for their catadromous migration: born in the ocean, maturing in freshwater, and returning to the ocean to reproduce. After spawning, adults die, and the next generation begins the cycle anew. Juveniles are strong explorers, capable of crossing wet ground to move between waterways.
