Silurus glanis Linnaeus,
1758
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his 'beasty' can grow up to 16ft in the wild and is definitely
not an aquarium fish unless kept in an indoor pool! where it could
grow to 9ft. There is actually 12 known species the world over,
and glanis is the type-species.
This is Europe's largest freshwater fish and is
only one of two catfish indigenous to Europe the other
from the same genus, Silurus aristotelis from the River
Akelhoos in Greece. This species looks like the other wels,
but its dorsal fin is smaller, and it has just two pairs of
barbels. The caudal fin is distinct from the anal fin.
The Common name for glanis is the 'Wels Catfish' and
is found in the Rhine River in Germany eastwards to the Black
and Caspian Seas.
The elongated wels body consists of a powerful forebody and
a laterally greatly compressed tail shaft; the prominent anal
fin merges with the caudal fin. This fish, with its calm undulating
tail movements normally has its long pair of upper jaw barbels
pointing straight forward, while the four smaller barbels of
the lower lip hang down. The dorsal fin, consisting of just
four rays, seems small for such a powerful animal.
What intrigues me most about this fish is the small size of
the dorsal (which is common in the Siluridae family)
compared to the size of the body and the long anal fin. Identification
of the Silurus genus relates to the long anal fin, small
dorsal fin with four or five rays without a spine, and minus
an adipose fin. The caudal fin is usually round to emarginate.
The name Silurus was used for some time for all naked
catfishes until Bleeker identified the distinguishing characters
of the various currently recognised groups. Silurus glanis
was actually the first catfish to be scientifically recorded
and it is synonymous to ScotCat as it is the first factsheet
to be produced. It had been introduced sporadically to Lakes
in England during the latter part of last century where clubs
have been formed, relating only to these fish, with videos being
produced of them being caught for sport in England, and other
parts of Europe.
A friend of mine actually went of to Spain to fish for them
in a Lake where they were seemingly introduced by a German ichthyologist
and he had a rare old time!. Altogether I think a very interesting
animal.
Dorsal 1/4; Anal 90-92; Pectorals; 1/14-17. Body elongate, cylindrical
anteriorly, compressed posteriorly. Head large and depressed.
Gape very wide. 3 pairs of barbels; the maxillary pair are especially
long and when laid back, reach to beyond the pectorals. The dorsal
fin is very small and inserted well forward. Adipose fin absent.
Anal fin-base very long.
Colouration extremely variable; usually fairly dark, the upperside
dark olive-green to blue-black and the flanks paler, occasionally
with a red-brownish sheen. Underside, especially the belly, pale.
Upon this ground colour are imposed cloudy or spotted marblings.
Entirely black-blue and quite pale individuals also occur. Fins
dark, red-brownish to brown-violet.
You can of course keep small Wels Catfish in an aquarium where
feeding is no problem with dim lighting and a large external filter
and they will eat anything ( just keep an eye on your household
‘cat’), but where would it go after outgrowing your
tank as Public Aquariums have probably their full quota.
| Sexing |
Females are larger in the ventral area in
the breeding season.
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| Breeding |
In their native habitat in the spring (May-July), the eggs are
laid in a shallow depression excavated by the male, the eggs can
total into the thousands and the growth is very rapid, with them
becoming sexually mature at between 4 and 5 years old and living
up to 20 or 30 years. There are even reputed reports of them living
to 80 years old!
In the wild they have been known to eat ducks where they rush
up behind them at night, sucking them into their mouths with a
vortex motion. In their native habitat they feed on other fishes
mainly eels, burbot, tench and roach, but it also takes water
voles as well as the ducklings.
| Etymology |
Silurus:
From 'silouros', a kind of river fish. Silurus,
sheetfish, catfish. According to Lacepéde
(1803) this word indicates the rapidity with which Silurus
can move its tail.
glanis: The name of a kind of fish.
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| Glossary
of Terms: |
Maxillary barbels
: Pertaining to the
upper jaw. (maxillary barbels)
Mandibular barbels : Pertaining to the
lower jaw. (mandibualr barbels)
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| Reference |
Wheeler, Alwyne Freshwater Fishes
of Britain and Europe 1983
Grzmeck's Animal
Life Encyclopedia Volume 4 Fishes 1,
1963
Sterba's Freshwater fishes of the World
Vol.1 1973
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| Photo
Credits |
Hans Reinhard
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