The waters around the world (outside the polar zones), are home to countless species of catfish. They are found so much in all fresh water low current (rivers, streams, lakes, ponds, ponds), in brackish water coastal rivers, and even in coastal marine areas.
With us, this fish, from the family of ictaluridae (order of siluriformes), native to America, was accidentally introduced into the Seine in the early 1870s and then spread by humans. He pursues a colonization slow, but steady European waters. The catfish enjoys a reputation for high resistancebecause it survives longer, out of water, than most fish.
Morphology of the European common catfish (Ameiurus melas)
Smaller here than in its native environment, this fish measures, on average, less than 30 cm in length, for a maximum weight of 300 g. Its skin without scales, of greenish tint, is unpleasant to the touch, because made viscous by the mucus which protects it and participates in the oxygenation of the organism. His mouth, flattened and disproportionate, is surrounded by 3 pairs of barbs, sort of long filaments pointing downwards and a pair of antennae above. Small inefficient eyes justify the presence of these tactile growths. Its large striped pectoral fins and dorsal fin are provided with poisonous prickles.
Another species, from the same family as the common catfish is in net progression in our rivers: the Catfish, up to nearly 3 m length for a weight of 150Kg. This animal is particularly pest.
The catfish is a opportunistic omnivore. Extremely voracious, it can feed on anything that comes within its reach. Yes small organizations living in the aquatic environment constitute a large part of its daily diet, it does not hesitate to seize small mammals, dead or alive, falling into water, young birds aquatic, of fish (including of its kind), of frogs, ofinsects, ofsnails, of towards, etc. It is also a formidable predator which loot the nests to swallow the eggs and ravage the fry spat. Occasionally, it also feeds on twigs of wood, ofalgae, ofherbs and other plants.
We must nevertheless recognize in these fish, often unloved, some environmental qualities. As a scavenger, they rid the fund of waste of all kinds, tirelessly plowing silt and mud. This feature is well known to aquarists who use some of the most sociable species to improve the cleanliness of the ponds. Less romantic, certain lakeside peoples of Asia raise colonies of catfish, to rid their underwater environment of the refuse they reject.
Catfish without borders
Catfish (including catfish) represent almost a quarter of the fish inhabiting the marine and fresh waters of the globe. They are even found in mountain lakes at very high altitudes. Official, unreliable figures are constantly changing and scientists are discovering new species every year. According to the sources, there could be between 35 and 45 families of siluriformes, distributed in more than 3,600 species (some speak of 4,500). Thus, on their own, catfish would represent 5% of vertebrates alive on planet Earth (including terrestrials)! They inhabit all the waters of the world, except those of polar regions. The greatest limitation of their morphological capacities seems to be their poor resistance to cold. Under 14 ° C temperature, most species go into hibernation.
Depending on the region, the size of the catfish varies from a few centimeters to several meters. For example, some catfish, such as Loricariidae well-known of our aquariums measure 3 to 4 cm long, while the Mekong catfish, reaching nearly 3 m long and 300 kg, is the largest known freshwater fish. None have scales, but the skin of some species is covered with a coating of bony plaques. The color, shape and appearance of the skin can be so different that the only recourse to classify them, for sure, lies in the form and the Constitution characteristic of their dentition. Indeed, only the jaws of catfish have a multitude of very small teeth distributed in plates.
Some amazing peculiarities of catfish
Like their physical abilities, the habits of catfishes vary ad infinitum. The three species inhabiting our rivers are generally solitary and thrive in murky bottom waters, but others, such as the Striped sea cats, live in huge, tight schools in clear, shallow marine coastal waters. Some Asian species even have the ability to change their non-communicating pools, “walking” short distances on the ground, leaning on their pectoral fins and on their tails. Several studies show that certain species of catfish can communicate between them. They use for this an original anatomical device putting the brain in relation with a network of bones and ossicles, the swimming bladder acting as a resonance chamber. This organic acoustic device, called Wéber device is distinguished from the inner ear of mammals by its embryological origin. Last item on this non-exhaustive list, some catfish oxygenate their blood through the skin, the mucus that covers it behaving like a sensor.
Catfish in the human diet
Catfish are already a protein intake, in vitamin D and in Omega 6, important for human food in most parts of the world. These fish, easy to rear in hot climates, constitute an industrial product dominating the economy of regions, even entire countries:
- In Europe, the production and consumption of catfish is increasingly popular, especially in eastern countries. French breeding is mainly concentrated in the center of the country (Sologne, Brenne, Limousin, etc.). However, the increase in the wild resource and by derivative effect, the multiplication of commercial siluform fisheries, have led many chefs to take an interest in this fish, and even to create specialty restaurants.
- Since the middle of the 20th century, the farms of Catfishwelded catfishrepresent a colossal market for the United States. The breeding of Clariidae and of Pangas is highly developed in Asian aquaculture farms, especially Vietnamese, and in African countries.
Good to know : The sanitary quality of Pangas (Pangasius) has been the subject of controversies widely publicized. In reality, this type of breeding is environmentally questionable, but it seems that this negative reputation is based on a bundle of controversies andallegations slanderous and without any real basis.
Catfish and sport fishing
The species of catfish introduced in Europe (Ictaiurus, Silures ..) become invasive, unbalance aquatic ecosystems and disrupt recreational fishing by jeopardizing the survival of native fish reserves. The French state has officially classified wild catfish “pest species“, which encourages its eradication. This involves banning fishermen from releasing catches and has given rise to a new profession: catfish trapper !