Barbels (whisker-like structures)
Many species have prominent barbels resembling a cat's whiskers, though not all catfish have prominent barbels.
Catfish
Catfish (order Siluriformes) are diverse ray-finned fishes named for their barbels, lacking scales and ranging from tiny parasitic species to very large commercial species.
catfishesNematognathi
Last Updated Mar 9, 2026 · 4 sources
Photo byFlaviu Sirbu
Species Guide
What to know about catfish
A clean field guide focused on habitat, identification, behavior, and conservation context without burying the useful parts.
Catfish (order Siluriformes, also called Nematognathi) are a diverse group of ray-finned fish. They are named for their prominent barbels, which resemble a cat's whiskers, though not all species have prominent barbels. All siluriformes lack scales and instead have either smooth skin or armour-plated bodies. The order is defined by features of the skull and swimbladder. Catfish vary greatly in size and behavior: some are among the largest freshwater fish (for example the Mekong giant catfish, the wels catfish, and the piraíba), while others are detritivorous or scavenging bottom feeders, and a few are tiny ectoparasitic species such as the candiru. Many larger species are farmed or fished for food (for example Pangasius and Clarias), and many smaller species (for example members of Corydoras) are kept in aquaria. In parts of the Southern United States, regional slang names for catfish include "mud cat", "polliwogs", or "chuckleheads", with different meanings in different places.
Catfish exhibit a wide range of behaviors and movement patterns: some species are large-bodied and range widely, many are bottom-dwelling detritivores or scavengers, and some tiny species are ectoparasitic.
Diet varies by species: many are detritivorous or scavenging bottom feeders, while some species are parasitic; others (including large species) are not described here as exclusively one feeding type.
Identification
How to identify catfish
The visual markers divers can use underwater, plus the species most likely to cause confusion.
Key identification markers
Lack of scales
All siluriformes lack scales and instead have either smooth skin or armour-plated bodies.
Skeletal and swimbladder features
The order is defined by distinctive features of the skull and swimbladder.
Range and Movement
How catfish move through the world
The broad range, seasonal movement, or migratory behavior that shapes where divers encounter this species.
Catfish exhibit a wide range of behaviors and movement patterns: some species are large-bodied and range widely, many are bottom-dwelling detritivores or scavengers, and some tiny species are ectoparasitic.
Diet
What catfish tend to eat
Useful feeding context that often explains habitat, movement, and encounter style.
Diet varies by species: many are detritivorous or scavenging bottom feeders, while some species are parasitic; others (including large species) are not described here as exclusively one feeding type.
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Responsible Encounters
How to dive with catfish
Conservation-minded guidance for divers who want the encounter without adding pressure.
Give catfish space, avoid blocking the animal's path, and follow local site and operator rules for wildlife interactions with freshwater fishes.
Field Notes
Interesting things worth knowing
Useful species context that makes the encounter more meaningful once you are underwater.
Field notes
Extremes in size
Catfish include some of the largest freshwater species (Mekong giant catfish, wels catfish, piraíba) and some of the smallest, including parasitic candiru.
Human uses
Many larger species are farmed or fished for food, and many smaller species are popular in aquaria.
Regional slang
In the Southern United States, regional slang names like 'mud cat', 'polliwogs', or 'chuckleheads' are used for catfish with varying meanings.
FAQ
Frequently asked questions
Clear planning and conservation answers written for search visibility and AI retrieval.
Research Sources
Catfish information sources
Primary and credible references behind the field-guide and conservation claims on this page.
Sources 4Last Updated
Catfish | Britannica · Reference · Britannica
Primary wildlife guide source.
U.S. Fish & Wildlife Service · Reference · U.S. Fish & Wildlife Service
Supporting wildlife source.
fishtreeoflife.org · Reference · fishtreeoflife.org
Supporting wildlife source.
Catfish · Encyclopedia · Wikipedia
Supporting wildlife source.
Related Species
More in Freshwater Fishes
Related species guides in the same encounter family.