Wels Catfish

Wels Catfish have an elongated scaleless body, a large head, tiny eyes, and a powerful forebody with a laterally compressed tail. The cavernous mouth has hundreds of rows of very small, gripping teeth on both its top and bottom jaws. The Wels Catfish has six barbules: those on the upper jaw are carried straight in front to detect prey, whilst the four shorter ones on the lower jaw hang straight down.

The Wels Catfish uses its jaws to grip prey before passing it to two sets of crushing pads at the back of the throat, where the prey is crushed. In addition, a number of short spikes on the edge of their gill rakers are used to manoeuvre prey, prior to it being swallowed whole. The teeth on the jaw are abrasive and care should be taken whilst handling them as contact with skin can result in a ‘graze’ like wound. One way to hold the jaw whilst unhooking is to place the thumb on the teeth of the bottom jaw whilst placing the forefinger is placed on the outside of the lower jaw to maintain a good grip.

The colouration of Wels varies greatly between individuals: usually with the back being fairly dark olive green to blue-black, giving way to paler flanks sometimes rusty in colour. This base colour is marbled with dark blotches and spots and gives way to a creamy yellow belly: providing near perfect camouflage for both stealth and low-level attack. The Wels Catfish is also seen in bright colours, ranging from bright orange and yellows, to albino looking forms with red eyes, whilst others grow almost entirely blue/black in colour. The fins are dark, ranging from red-brown to brown-violet.

The Catfish is not indigenous to Britain, but inhabits mainland Europe and Asia. The species was introduced to England from Germany in the late 1800s, with 70 being stocked into The Shoulder of Mutton Lake at Woburn Abbey in Bedfordshire in 1880, having been received as a gift to the British Ambassador in Berlin. It is believed that their introduction was linked to the ‘gentleman’s pastime of introducing alien species of plants and animals and secondly as a cheap source of protein with which to feed the Victorian working classes, on whom their wealth depended.

In the 1860’s, in anticipation of the possible use of Wels Catfish to feed the masses, “The Times” newspaper suggested that the fish was “the most important animal introduction since the bringing of the turkey”, describing the flesh as “veal with a rich eel-like flavour, superior to salmon.” However, the use of the Wels Catfish as a food source does not appear to have been as successful as was anticipated.

The British Record Fish Committee unfortunately stopped accepting record claims for Wels Catfish and closed the record list (see above), this followed a period of illegal fish smuggling into England from mainland Europe, during which some claims were submitted citing fisheries with no known history of Wels Catfish being present. The European record for the Wels Catfish is 316lb 8oz (that’s an incredible 144kg & 2.78m long), ironically caught from the River Po in Italy where they were also introduced as an alien species.

However the rod caught records are dwarfed by 600lb + specimens caught by Russian trawlers, with scientific studies of Wels’ bones suggesting that a maximum size of 1,000lb is possible, believed to inhabit the vast Russian lakes where commercial trawling ships are unable to fish. Although White Sturgeon (Huso huso), grow to weights of 2,200lb, they spend much of their life at sea, and it is quite possible that Silurus glanis is the largest freshwater fish in the world.

Spawning takes place when the water temperatures approach 20 degrees C, usually between May and July. Males excavate a shallow depression in which the eggs are laid in their thousands, with each female depositing anywhere between 8,500 – 12,000/kg of her weight. Depending on temperature, eggs hatch after 3 days, the larva of about 7mm long have one barbule and initially feed on plankton. They develop predatory habits and feeding on small fish, insect larvae and other aquatic prey. The ‘kittens’ as they are known, can grow rapidly in ideal conditions, attaining weights of 1lb within a year and able to reach 5lbs in just three years. They can become sexually mature between 4-05 years old and often live to 30-years in age. Evidence has shown that Wels of 180lb caught in Continental Europe have been as young as 24-years old, so consider how old the enormous specimens that inhabit the freshwater lakes of Russia may be ! Only time will tell how large they grow in British waters.