Wels CatfishSilurus glanisWhere and when to see them

The Wels catfish is one of Europe's largest freshwater fishes, with a broad head, a powerful body and conspicuous whisker-like barbels. It is native to much of central and eastern Europe, including the Danube basin. It is also established in the Rhine and Saône, within a western European distribution expanded by introductions. Despite its impressive size, this mostly submerged predator is much less conspicuous to river travellers than birds or surface-feeding fish.

Size

Commonly 1–2 m long as a mature adult; exceptional individuals exceed 2.7 m.

Weight

Large adults can weigh several tens of kilograms; exceptional individuals exceed 100 kg.

Lifespan

Often 20–30 years, with some individuals living considerably longer.

Status

Least Concern (IUCN).

Wels catfish are often most active at dusk and during the night, although daytime activity also occurs. They frequently rest near the bottom or beside submerged cover between feeding periods. Their barbels and other sensory systems help them locate food in darkness and turbid water. Activity generally increases as water warms and decreases during colder months. Individuals may gather at sheltered resting sites or in deeper winter refuges. Spawning takes place in late spring or summer when the water is sufficiently warm. The male prepares and guards a nest, protecting the eggs and fanning them with water until they hatch.

• Its whisker-like barbels are sensory organs, not stingers.
• Its skin has no scales and is covered by protective mucus.
• Males guard the eggs and fan them to improve water circulation.
• At a few studied sites, individuals have learned to catch pigeons at the water's edge.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

This species inhabits large rivers, lakes, reservoirs and connected backwaters. It favours warm, relatively slow-moving water with deep refuges and access to feeding areas. Submerged wood, undercut banks and other sheltered structures provide daytime resting places. Shallow, vegetated margins can offer suitable spawning habitat. Along the Danube, Rhine and Saône, suitable habitat occurs in both the main river and quieter connected waters, although local abundance varies.

Wels catfish are opportunistic predators whose diet changes with size and local food availability. Young fish eat aquatic invertebrates and small fish. Larger individuals consume fish, crayfish and other available animals, including amphibians. Waterbirds and small mammals are occasionally taken, but these should not be regarded as the normal diet everywhere.

Common name

Wels Catfish

Scientific name

Silurus glanis

Animal group

Fish

Size

Commonly 1–2 m long as a mature adult; exceptional individuals exceed 2.7 m.

Weight

Large adults can weigh several tens of kilograms; exceptional individuals exceed 100 kg.

Lifespan

Often 20–30 years, with some individuals living considerably longer.

Status

Least Concern (IUCN).

Identification

Look for a broad, flattened head, a very wide mouth and six barbels: two long ones on the upper jaw and four shorter ones beneath the lower jaw. The elongated, scaleless body is usually dark and mottled above, with a paler underside. A tiny dorsal fin contrasts with a very long anal fin extending along much of the underside towards the tail. These features distinguish it from smaller introduced bullhead catfish, which have eight barbels and an additional fleshy adipose fin.