WELS CATFISH: THE SILURO

                                                            Roberto Ferrario

FAMILY: Siluridae. Catfish:- There are about a dozen members of this family which includes Silurus asotus from Japan, Silurus berdmorei from India and Silurus gilberti from China. However, in Europe the main two groups are wels; Silurus glanis and the Aristotles Catfish (Silurus aristotels). The latter is very similar to the wels, but only possesses two barbules under the lower jaw, whereas the wels has four.

The Wels is easily recognized by its huge wide mouth, it has six whiskers, two long ones on the upper jaw, and four smaller ones under its chin. They are also characterized by their long anguilliform bodies and their lack of obvious scales. They have one very small dorsal fin and an elongated anal fin; this stretches for half of the fishes' body. They have a row of small "sand-paper" like teeth on both the top and bottom jaws. Each row consists of hundreds of teeth and these predominantly soft and are used to grip the prey; they slope inwards toward the back of the mouth. In front of the throat cavity are two crushing plates, which the wels use to squash its prey prior to swallowing. They also have a number of short spikes on the edge of the gill rakers. These are used to manipulate their pray prior to swallowing. Although this description might sound horrible it is quite safe to put your hand (and arm) into a catfish's mouth as the teeth are soft and only occasionally scratch. One way to carry the wels is called the "Waller grip", where the thumb is placed on the teeth and the forefinger is placed under the cats jaw for grip.

SPECIES: The European Wels Catfish - Silurus glanis
 

Distribution: The wels is naturally distributed all over Eastern Europe and Asia with high concentrations in the Danube and Volga basins. Through the intervention of man the wels has since found its way into many rivers and lakes in Germany, France, Spain, England and Holland. Silurus glanis has many different pseudonyms. In Holland it is known as "Meerval", in Russia "Ssum", Czechoslovakia "Sumec", Spain "Siluro", Germany "Wels or Waller", and in France "Silure". But In Britain, it is simply referred to as the "Catfish", a name which could apply to many thousands of species world wide and often causes confusion. The catfish is widely distributed, but has a greater concentration in the counties of Bedfordshire, Buckinghamshire, and Cambridgeshire. The wels is not indigenous to this country and they were first introduced into the "Shoulder of Mutton Lake" at Woburn Abbey in Bedfordshire on 27/10/1880. Since then they have been stocked both legally and illegally into many lakes throughout the country.
 

Size: In Russia "Ssum" is frequently caught at 600lb+ by trawlers. In Germany, France and Spain they are caught at over 100 lb with a 100lb cat usually attaining over 6 feet in length. However, in England the record catfish currently stands at 57lb 4oz. Through a study of bones it is thought that a maximum size for this species is around 1,000lb and such specimens are thought to live in some of the big Russian lakes where the commercial trawling vessels cannot fish; the local anglers use baby pigs for bait. In freshwater the catfish's size is only surpassed by that of the white sturgeon (Huso Huso) which may attain weights of 2,200lb, however, the sturgeon is not regarded as a freshwater fish as most of its life is spent at sea. Therefore, Silurus glanis is the largest freshwater fish in the world.

Behavior: Catfish are especially suited to the slow-flowing reaches of the larger rivers and lakes especially with dense weed-beds and muddy bottoms. However, catfish are very adaptable and can even be found in the strongest currents of the River Po in Italy where fish up to 200 lb can be seen feeding under boiling water conditions where the current is so strong that boats are unable to anchor. Silurus glanis is mainly a nocturnal scavenger and feeds best in warm weather at night. In the UK they spend many days without feeding and then gorge themselves. On the continent, where the water is warmer, they feed more intensively. Though mainly a scavenger feeding on mussels and crayfish catfish will also feed on live fish that are located by using its long whiskers to feel vibrations given off by injured fish. Diet: The diet of catfish is mainly dead or live fish. However, larger specimens will eat most things including frogs, rats, coypu and snakes. In Russia several specimens have been found with human remains in their guts, although it is thought that the individuals drown first - then are eaten whole. There has never been a reported incident of catfish attacking divers, however, they do attack boats, but this is thought to be a territorial response.