Wels Catfish (Silurus glanis) Care Guide
Silurus glanis is one of the largest freshwater fish in Europe, a cold-water predator suitable only for public aquaria.
Compiled by Aquairi from published sources · Published · Updated
Overview
Silurus glanis, the wels catfish, was described by Linnaeus in 1758. It is a large predatory catfish native to Europe and parts of western Asia, and one of the largest freshwater fishes in Europe. Owing to its eventual size it is suitable only for very large public aquaria and ponds, not home tanks.
Taxonomy
- Family: Siluridae
- Genus: Silurus
- Scientific name: Silurus glanis
Habitat
FishBase records the species from the North, Baltic, Black, Caspian and Aral Sea basins, as far north as southern Sweden and Finland, and it has been widely introduced across Europe. It inhabits large and medium lowland rivers, backwaters and well-vegetated lakes, and can tolerate brackish water in the Baltic and Black Seas.
Tank requirements
- Minimum volume: 5000 L or more; realistically a public-aquarium or pond species
- Temperature: 4-24 °C (39-75 °F); FishBase lists 4-20 °C
- pH: 6.5-8
- GH: 8-20 °dGH
- Depth in nature: 0-30 m (FishBase)
- Lifespan: about 8-15 years in care; FishBase records a maximum age of 80 years
Diet
FishBase classifies it as a nocturnal predator: juveniles eat invertebrates and small fish, while adults prey on fish and aquatic vertebrates. Wikipedia notes large specimens also take crayfish, eels, frogs, rodents and even aquatic birds. It is a carnivore best fed once daily on meaty foods.
Compatibility
This is an aggressive, bottom-dwelling predator that will consume any tankmate small enough to swallow. It should not be combined with small fish. Only similarly large, robust species in very large systems are appropriate, and it is largely nocturnal.
Conservation status
IUCN Red List: Least Concern (FishBase cites an assessment dated 29 May 2022). Wikipedia notes the species is locally declining in northern peripheral populations such as Sweden, while being regarded as invasive where introduced.
Silurus glanis (Wels Catfish) Breeding Guide
Overview
Silurus glanis, the wels catfish, is one of the largest freshwater fishes in Europe and a member of the family Siluridae. According to Wikipedia it is native to wide areas of central, southern and eastern Europe, in the basins of the Baltic, Black and Caspian Seas. Most adults are 1.3 to 1.6 m long; the longest recorded specimen measured 2.85 m (2023) and the heaviest authenticated catch weighed 134.97 kg.
Spawning Behaviour & Trigger
Wels catfish are highly fecund: according to Wikipedia, a female produces up to about 30,000 eggs per kilogram of body weight. After spawning, the male takes on parental responsibility and guards the nest throughout development. The species is a nest spawner, with the male defending the eggs until they hatch. Given that wild adults are most often 1.3 to 1.6 m long, even an average female can carry a very large number of eggs, which underlines why spawning happens on a scale far beyond aquarium dimensions.
Egg & Fry Care
Egg incubation depends strongly on water temperature, with hatching taking from three to ten days according to thermal conditions. The guarding male shows notable parental care: if water levels fall too quickly he has been observed to splash the eggs with his tail to keep them wet. This intensive male care continues through the vulnerable egg stage.
Common Challenges
Because adults reach several metres and tens of kilograms, and because spawning, nest defence and the huge egg masses occur on a scale suited to large ponds, lakes and rivers, deliberate reproduction is the domain of aquaculture and public aquaria. Home reproduction is impossible; the species should not be kept where it cannot reach full size safely.