Wels Catfish

Yuri Wels

Yuri Grisendi with a monster wels!

By: Yuri (ElDiablo) Grisendi

Silurus glanis, commonly known as the wels catfish, is a European freshwater fish belonging to the family of Siluridae and order Siluriformes.  It is native to Eastern Europe, the Danube basin to the east.  It is naturally present in all of Central and Eastern Europe, as far west as Austria and Germany (Danube basin), north to the extreme south of Finland and Denmark and as far south as northern Greece and Turkey to the European Union.  Wels were introduced in Great Britain, Holland, Belgium, Germany, France, Spain, Italy, Denmark, Finland, Sweden and in some areas outside Europe including Algeria, Cyprus, Tunisia, China and Afghanistan.  They have also been found in the salt waters of the Aral Sea, near the peninsula Kulandy.
In Italy wels were introduced half a century ago and are especially prolific in the basins of the Po and Adige, and more recently have been introduced in the rivers Arno and Tiber.
Ideal habitat consists of large rivers, but also includes marshes, ponds, lakes, oxbow lakes, oxbows and drainage channels.  Wels occasionally approaches the sea, near the mouths of large rivers, but it is not yet clear if they frequent brackish waters.  They commonly associate with the bottom of a body of water and usually live in the deepest parts but will venture to shallower waters, especially during hunting.  Wels will typically hide among branches and mud, resting during most of the day. With the reach of darkness they begin to feed, often moving very shallow and even surface feeding.

The appearance of this big fish is quite unique.  They have a cylindrical body that thins and compresses more and more towards the tail. The big mouth is equipped with three pairs of barbels, one pair on the jaw and two on the lower jaw, which help the fish in locate food. The caudal fin is delta, short and squat, the thin chest, as well as the dorsal and ventral. The anal fin is rather long.
The color is lighter on the belly, brown on sides and back, marbled with brown and white. It is devoid of scales and totally covered with mucus.
In very clear waters – British waters, large Italian alpine lakes, streams, piedmont – shows colorations tend to emphasize the contrast between black back and white belly. In the murky waters – lakes very organic, oxbows death of deltas Kazaks, quarries and ponds of the lower course of the Adige – assumes brownish color until you reach the yellow streaked with brown, typical of the specimens that live in swamps.
Wels can grow to enormous sizes depending on the habitat in which it is located. In Kazakhstan and along the courses of the rivers Danube, Po and Ebro, reaches its maximum size, which is about 280cm, which is just over 9 feet!  In the river Arno Wels appear to have a higher rate of growth, while in Britain and Denmark they rarely exceed 170cm. Recent surveys have found that wels between 146cm and 180cm on average 16-18 years. In this sense, the biggest specimens could be up to 25-30 years of age.
The catfish is one of the major predators of inland waters and feeds on dead and live fish, worms, larvae, etc.  Specifically, during the juvenile stage its forage is composed of bottom invertebrates, while in the adult stage is fed to fish such as eel and carp.  The amount of fish they eat daily is equal to 3% of its body weight in adult specimens and is 10% while at a young age.  Wels are a fast and powerful predator but do not have great sight. Their main weapon are their barbels, which allow them to locate prey in the dark and in murky, muddy water.
Many legends revolve around the aggression and greed of the wels.  Among them, are stories of vicious attacks on dogs, cattle, children and divers. Scientific documentation shows very aggressive behavior during the reproductive period and under particular stress.  The wels is a particularly versatile predator in the adult stage can adapt strategies to the type of hunting prey more readily available in the environment in which they live, whether they are fish, small mammals, waterfowl and birds. Several scientific studies have shown that a significant proportion in the diet of larger species is based on small mammals and waterfowl.
After mating, which occurs when the water temperature exceeds 20 ° C (68°F), the female lays her eggs, which are then cared for by the male until the fry are independent.
Threatened in their home countries from over-fishing, pollution and the construction of reservoirs and dams in the waters in which it was introduced is a source of problems and dramatic impacts on native populations. The rivers of northern Italy were compromised, for example by channeling and drainage that have totally eliminated environmental situations such as reeds and shallow areas that are very important for reproductive purposes for a number of species including wels, tench and pike. The disappearance of the sturgeon,the introduction of numerous dams, and the slow disappearance of the pike, have greatly facilitated the permanent settlement of the wels in Italian waters. The introduction of other non-native species, like carp and bream, did the rest by providing a huge amount of prey for this large predator. Because of the wels large size and aggressive nature, it sits at the pinnacle of the food chain. It should be reminded that the torpedo has been established now for over half a century in Italian waters. In certain areas of the country they have taken measures to safeguard native species by prohibiting the release of any other non-native invasive species. In northern Italy there is great interest in the preservation of the wels for both sport and economic reasons.  In the province of Rovigo, investigations have shown that on average 27% of the biomass of the river Po consists of the wels catfish.

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