Bryan McAllister’s personal reference notebook
July 27, 2026Short & citedBlog
Civic Viewpoint.
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Field Notes • Fish

Catfish

Catfish are a diverse group of ray-finned fish in the order Siluriformes, known for their whisker-like barbels around the mouth and lack of scales.

Updated July 27, 20261 min readCited sources

Catfish are a diverse order of ray-finned fish known for their whisker-like barbels and scaleless bodies. Most species live in freshwater, but some inhabit marine or brackish waters.

What it is

Catfish belong to the order Siluriformes. They are identified by barbels near the mouth, a broad head, and usually scaleless skin. Sizes range from small species to giants over 2.5 metres long, and their diet varies widely by species.

Habitat and ecology

Most catfish live in freshwater environments such as rivers, lakes, and wetlands, though some species tolerate brackish or marine waters. They are bottom-feeders adapted to murky water, using their barbels to locate food. They play important roles in aquatic food webs.

Human use and Canadian context

Many catfish are harvested or farmed for food, especially in aquaculture. In Canada, they are familiar to anglers and aquarium hobbyists, but most species prefer warmer freshwater systems than Canada’s colder native lakes and rivers.

In short

  • Catfish are an order (Siluriformes), not a single species.
  • They are named for whisker-like barbels around the mouth.
  • Most catfish are freshwater, bottom-dwelling fish.
  • Sizes range from tiny to over 2.5 metres long.
Canadian angle

Catfish are familiar to Canadian anglers and aquarium hobbyists, but most species associated with the name are native to warmer freshwater systems rather than Canada’s colder regions.

Quick questions

What is a catfish?
A catfish is any fish in the order Siluriformes, a group known for whisker-like barbels around the mouth and usually scaleless bodies.
How big do catfish get?
Catfish range from small species to giant forms that can exceed 2.5 metres in length and over 100 kilograms in weight.
Where do catfish live?
Most catfish live in freshwater habitats such as rivers, lakes, and wetlands, though some species live in brackish or marine waters.

Sources

  1. Merriam-Websterhttps://www.merriam-webster.com/dictionary/catfish
    Supports: Definition of catfish as a fish in the order Siluriformes with barbels and usually freshwater habitat.
  2. Cambridge Dictionaryhttps://dictionary.cambridge.org/us/dictionary/english/catfish
    Supports: Definition of catfish as a fish with a flat head and long whisker-like structures living in rivers or lakes.
  3. Britannica Dictionaryhttps://www.britannica.com/dictionary/catfish
    Supports: Definition of catfish as a fish with a large head and whisker-like mouth parts.
  4. Wikipediahttps://en.wikipedia.org/wiki/Catfish
    Supports: General overview of catfish diversity, size range, and the order Siluriformes.
  5. Langeekhttps://www.langeek.co/en/word/30073?entry=catfish
    Supports: Habitat, feeding behaviour, and examples of catfish ecology across freshwater and saltwater environments.
  6. Simple English Wikipediahttps://www.simple.wikipedia.org/wiki/Catfish
    Supports: Broad overview including very large species and general note that most catfish do not harm people.