Wels Catfish

About

The wels is the largest freshwater fish in Europe, and it is occasionally offered as a hand-length juvenile with long whiskers and a comically wide mouth. FishBase is unusually blunt about both the animal and the folklore: the five-metre, 306 kg wels of the old literature was misidentification and confused units, and the largest specimens supported by evidence are 2.73 m and 130 kg. That is still, by a distance, the biggest fish in any Lithuanian lake. Most adults settle between 1.3 and 1.6 m and anything over 2 m is a rarity; the heaviest authenticated fish, taken from the river Po in 2010, weighed 134.97 kg, and the longest on record is an unweighed 2.85 m fish from the same river in 2023. It is native here — common in rivers, lakes and the brackish Curonian Lagoon — nocturnal, bottom-oriented, and it swallows whatever it can get its head around: fish, crayfish, frogs, waterfowl. Seriously Fish gives it eighty years and more, and FishBase records a maximum age of 80. There is no aquarium answer to this animal. Seriously Fish declines to publish a tank size at all, writing only that the species is suitable for public aquaria plus a very small minority of private aquarists, and adds that a carefully aquascaped planted set-up is obviously out of the question.

Care

A pond fish, and an enormous one — the honest answer about a tank is that there isn't one. Plan on a deep outdoor pond of the order of 50,000 litres with eight metres of open swimming length and a metre and a half of depth, sand or bare bottom, sunken timber and pipe to hide under, dim light and a filter system Seriously Fish calls mandatory and enormous. One fish: it is not gregarious and is normally territorial towards its own kind. Every companion has to be too big to swallow, and it lives at 4–20 °C, so a heated tropical tank is wrong twice over. Where the rules matter: in Lithuania the wels is a native, legally fishable species — the amateur fishing rules set a minimum size of 75 cm, a limit of one fish per outing and a closed season from 1 November to 1 April — but moving or releasing wild animals is not free. The Ministry of the Environment states that anyone intending to release or translocate wild animals must notify the Environmental Protection Department and obtain its approval, and that introduction or reintroduction requires a permit from the Environmental Protection Agency. The United States takes the opposite view of the same fish: 50 CFR 16.13 lists Silurus glanis by name as injurious wildlife, so importing it or moving it between states is prohibited except under permit. Other countries differ again — check the rules where you actually live before buying anything.

Diet

Nocturnal opportunistic carnivore: fish and crustaceans mostly, with amphibians, insects and young waterfowl taken as well. Captive fish accept prawn, mussel, squid, whitebait and strips of white fish. No mammalian meat as a staple, and far less food than it will cheerfully accept.

Telling males from females

There is no reliable way to sex this species by eye. That is the honest answer, not a gap in our data.

Also in these lists

Similar species

Same category and the closest water parameters — if this species isn't quite it, start here.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

These links are unpaid: we get nothing for them and ask for nothing.

Frequently asked questions

What tank size does a Wels Catfish need?

A Wels Catfish needs an aquarium of at least 50000 litres (13208.6 US gallons) with a footprint at least 800 cm (315 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Wels Catfish need?

Wels Catfish does best at 4–20 °C (39.2–68 °F), pH 6–8 and a general hardness of 3–25 °dGH.

Is the Wels Catfish suitable for beginners?

Wels Catfish is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.

Sources

• FishBase — Silurus glanis (Wels catfish)
• Seriously Fish — Silurus glanis (Wels catfish)
• Wikipedia — Wels catfish
• Vikipedija — Paprastasis šamas
• eCFR — 50 CFR 16.13, importation of live or dead fish, mollusks, and crustaceans (current text)
• Lietuvos Respublikos aplinkos ministerija — Keičiasi laukinių gyvūnų, augalų ir grybų rūšių introdukcijos, reintrodukcijos ir perkėlimo reikalavimai
• Medžioklė ir žvejyba — Žvejybos taisyklės, mažiausi leidžiami sugautų žuvų dydžiai
• Agrožinios — Sodybos vandens telkinio įžuvinimas
• e-TAR — Mėgėjų žvejybos vidaus vandenyse taisyklės (aplinkos ministro įsakymas Nr. D1-14, suvestinė redakcija)