Body shape
Eel-shaped, elongated body typical of Anguilliformes and other eel-like fishes.
Eel
Eels are eel-shaped, ray-finned fishes of the order Anguilliformes, mostly marine predators with complex larval-to-adult development.
Anguilliformes (true eels)
Last Updated Mar 9, 2026 · 3 sources
Species Guide
What to know about eels
A clean field guide focused on habitat, identification, behavior, and conservation context without burying the useful parts.
Eels are ray-finned fishes in the order Anguilliformes, comprising eight suborders, 20 families, 164 genera and about 1,000 species. They undergo considerable development from an early larval stage to the adult form and are usually predators. The common name "eel" is also applied to unrelated eel-shaped fishes such as electric eels (genus Electrophorus), swamp eels (order Synbranchiformes), and deep-sea spiny eels (family Notacanthidae). Most eels are marine, but some taxa have different life histories: the catadromous genus Anguilla and the freshwater moray spend much of their life in freshwater, the rice-paddy eel spawns in freshwater, and the freshwater snake eel Stictorhinus is freshwater-associated. Deep-sea spiny eels (Notacanthiformes) are the sister clade to true eels.
Most eels are marine, but some taxa have different movement and life-history patterns: the genus Anguilla is catadromous (migrating between freshwater and the sea), some species like the rice-paddy eel spawn in freshwater, and other taxa (e.g., freshwater moray, Stictorhinus) spend much of their life in freshwater.
Eels are usually predators.
Identification
How to identify eels
The visual markers divers can use underwater, plus the species most likely to cause confusion.
Key identification markers
Taxonomic placement
True eels are ray-finned fishes in the order Anguilliformes.
Development
Marked development from an early larval stage to the adult form.
Feeding
Generally predators.
Common lookalikes
Electric eels (Electrophorus)
Eel-shaped but belong to a different genus and are not true eels.
Swamp eels (order Synbranchiformes)
Eel-shaped fishes from an unrelated order.
Deep-sea spiny eels (family Notacanthidae)
Eel-shaped deep-sea fishes in Notacanthiformes, the sister clade to true eels.
Range and Movement
How eels move through the world
The broad range, seasonal movement, or migratory behavior that shapes where divers encounter this species.
Most eels are marine, but some taxa have different movement and life-history patterns: the genus Anguilla is catadromous (migrating between freshwater and the sea), some species like the rice-paddy eel spawn in freshwater, and other taxa (e.g., freshwater moray, Stictorhinus) spend much of their life in freshwater.
Diet
What eels tend to eat
Useful feeding context that often explains habitat, movement, and encounter style.
Eels are usually predators.
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Responsible Encounters
How to dive with eels
Conservation-minded guidance for divers who want the encounter without adding pressure.
Give eel space, avoid blocking the animal's path, and follow local site and operator rules for wildlife interactions with saltwater fishes.
Field Notes
Interesting things worth knowing
Useful species context that makes the encounter more meaningful once you are underwater.
Field notes
Diversity
True eels include about 1,000 species across 20 families and 164 genera.
Name usage
The common name "eel" is also applied to several unrelated eel-shaped fishes.
Sister clade
Deep-sea spiny eels (Notacanthiformes) are the sister clade to true eels.
FAQ
Frequently asked questions
Clear planning and conservation answers written for search visibility and AI retrieval.
Research Sources
Eel information sources
Primary and credible references behind the field-guide and conservation claims on this page.
Sources 3Last Updated
Eel | Description, Types, & Facts | Britannica · Encyclopedia · Britannica
Primary wildlife guide source.
www.fws.gov · Reference · fws.gov
Supporting wildlife source.
Eel · Encyclopedia · Wikipedia
Supporting wildlife source.
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