West American catfish
|West American catfish|
West American catfish ( Ariopsis seemanni )
|( Günther , 1864)|
The West American catfish ( Ariopsis seemanni , Syn . : Sciades seemanni , Arius seemani ) belongs to the family of the Ariidae ( cross catfish ). It is a fish that lives in river mouths in brackish water ; as an adult, it lives mainly in sea water. Small fry (up to 3 cm) live temporarily in fresh water.
The West American catfish is somewhat similar to a shark and is therefore - improperly - offered as a "mini shark" in specialist aquarium stores.
The species lives in the seawater and brackish water of American rivers flowing into the Pacific, from southern California and Mexico in the north to Colombia, Ecuador and Peru in the south.
Way of life
The West American catfish lives mainly predatory and feeds on smaller fish, crabs , etc. Sometimes, however, you can also observe green fodder intake. In terms of social behavior, it also shows interesting properties for a predatory fish. It is almost never to be found alone until its full adult development. The fry even seem to practice hunting in groups.
Cross catfish are mouthbrooders . Reproduction in captivity has not yet succeeded.
West American cross catfish can grow to be 35 to 45 cm long. Statements that they can even reach a length of well over 100 cm are based on confusion with similar species.
The fish has poisonous spines on its dorsal fin for defense. The poison inhibits blood clotting . This can sometimes lead to the victim bleeding to death internally. The West American catfish is harmless to humans, but allergy sufferers should be careful. Another special feature is that the animals make clearly audible sounds for humans outside the aquarium. This seems primarily to serve the communication between the animals. Sound formation does not play a role in the detection of food.
Because of its shark-like appearance, this fish is often kept in aquariums . Most aquarists use fresh water , which however does not correspond to the natural habitat. According to this unsuitable animal husbandry, the lifespan of the West American cross catfish in freshwater is very limited. The Austrian 2nd Animal Husbandry Ordinance describes the species - as the only one of the numerous species listed - as "not suitable as an aquarium fish!"
A species-appropriate keeping in aquariums is only given in a real brackish water aquarium . A tank size of at least 800 liters and the willingness to convert the aquarium to seawater later should be given. Mini-sharks live most of their lives in river foothills, called estuaries , or brackish water zones. Young mini sharks are born in fresh water, upstream. The mini sharks live in fresh water up to a size of three centimeters. This is sometimes the reason why many retailers assume that mini sharks are freshwater fish and do not warn buyers that keeping mini sharks in freshwater will result in a correspondingly low life expectancy. As soon as the young animals are larger than three centimeters, they move downstream in the fresh water, called brackish water , which is enriched by the seawater . They prefer a density of 1.005 to 1.010 grams per cubic centimeter (1.001 g / cm³ corresponds to 1.17 grams of salt per liter) up to a size of ten centimeters. Later on, a density of 1.010 to 1.018 g / cm³ is recommended. Adult animals later move out into the open sea. The life expectancy of a mini shark is 15 to 17 years. According to a US statistic, 85 percent of all mini-sharks kept in freshwater die within the first three months. In saltwater aquariums, the animals can easily live to be more than 10 years old, even in captivity. The species-appropriate keeping in salty water is therefore to be regarded as absolutely essential.
- West American catfish on Fishbase.org (English)
- Ariopsis seemanni in the Red List of Threatened Species of the IUCN 2013.1. Posted by: Cooke, R., Acero, A., Betancur, R., Rojas, P. & Cotto, A., 2010. Retrieved September 4, 2013.
- Total legislation for the second animal husbandry Regulation on ris.bka.gv.at . Retrieved September 9, 2014.