Catfish (order Siluriformes) are a diverse group of
fish. Named for their prominent "barbels", which give
the image of cat-like whiskers, they are found in freshwater environments
of all kinds, with species on every continent except Antarctica.
Some species from the families Ariidae and Plotosidae are also found
in marine environments. They feature some of the smallest known
vertebrates, including the candiru, the only vertebrate parasite
to attack humans, as well as Pangasius gigas, the largest reported
freshwater fish. There are armour plated types and also naked types,
but they do not have scales. Not all catfish families have barbels;
what defines a fish as being in the Siluriformes order are certain
features of the skull and swimbladder.
have no scales. All catfish, except members of Malapteruridae (electric
catfish), possess a strong, hollow, bonified leading ray on their
dorsal and pectoral fins, through which a stinging protein can be
delivered if the fish is irritated. In members of the family Plotosidae,
and of the genus Heteropneustes, this protein is so strong it may
hospitalize humans unfortunate enough to receive a sting.
Catfish range in size and behavior from the heaviest, the Giant
Mekong Catfish (Pangasius gigas) in Southeast Asia and the longest
Wels Catfish of Eurasia, to detritivores (species that eat dead
material on the bottom), and even to a tiny parasitic species commonly
called the candiru (Vandellia cirrhosa).
The wels catfish (Silurus glanis) is the only native catfish species
in Europe, besides the much smaller related Aristotle catfish found
in Greece. Mythology and literature record wels catfish of astounding
proportions yet to be scientifically proved. The average size of
the species is about 1,2m-1,6m, and fish more than 2m are very rare.
The largest specimens on record measure more than 2.5 in length
and sometimes exeeded 100kg. The wels catfish was introduced to
Britain, Italy, Spain, Greece and some other countries during the
last century. The species has flourished in the warm lakes and rivers
of Southern Europe. The River Po in Italy and the River Ebro in
Spain are famous for huge wels catfish, which grow up to 2m. These
habitats contain plenty of food and lack natural predators.
Catfish, which have a sweet, mild flesh, are important food fish
throughout the world. Ictalurids are cultivated in North America
(especially in the Deep South), and representatives of the genus
Ictalurus have been misguidedly introduced into European waters
in the hope of obtaining a sporting and a food resource, however,
the European stock of American catfishes have not achieved the dimensions
of these fishes in their native waters, and have only increased
the ecological pressure on native European fauna, while Clariids
and Pangasiids are heavily cultured in Africa and Asia. There is
also a large and growing ornamental fish trade, with hundreds of
species of catfish, especially the genus Corydoras, being a popular
component of many aquaria.
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