Blueband harlequin
| Blueband harlequin | ||||||||||||
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Blueband harlequin |
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| Systematics | ||||||||||||
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| Pseudorasbora parva | ||||||||||||
| ( Temminck & Schlegel , 1846) |
The stone moroko ( Pseudorasbora parva ) is a species from the family of carp fish (Cyprinidae). It originally comes from Asia , but was introduced by humans in many regions of Asia and Europe .
features
The blueband barbel are small (up to 95 mm total length, on average 30 to 75 mm) soft-finned fish that are similar to the gudgeons ( gobio ). It is unusual for the family that the male bluebirds are on average larger than the females. The body height is about a quarter of the length. The body is quite slim and torpedo-shaped. Overall, the morphological features are very variable. Depending on the origin of the animals, not only the coloration, but also the shape of the fins, for example, is very different. The basic color of the individuals found in Europe is a greenish gray. Behind the back this turns brownish. The lower body area, i.e. the flanks below the sideline , as well as the gill cover are shiny silver. This luster is very noticeable and pronounced in the young fish, but disappears with increasing age of the fish and then becomes darker and darker. The animals often appear spotted on a regular basis. This comes from the dark spots on the rear edge of the relatively large scales . With some animals - depending on the incidence of light - these can be drawn out into a dark edge of the scales, so that a reticulate pattern , similar to that of guppies ( Poecilia reticulata ), is created. The sideline runs from the mouth to the middle of the tail fin base almost straight and continuously along the middle of the body. It is usually quite wide and dark. It occurs most clearly in young fish and females. In the case of the males, it can recede entirely. The fins are usually translucent to yellowish white or slightly darker in color. The dorsal fin often has a broad, diffuse band that runs transversely to the fin rays . At spawning time , the body color, especially of the males, can differ from the common ones. Also spawning rash was observed. The head and the gill covers are often purple to reddish blue in the males and sulfur yellow in the females. Again, there can be big differences depending on the subspecies .
The anal fin has 5 or 6 (rarely 7) rays and begins only behind the end of the dorsal fin base. The caudal stalk is noticeably high, the caudal fin incised almost halfway. Overall, the fins in European animals are well rounded, in Chinese subspecies more angular. The mouth is very small, overhead and directed obliquely upwards. The sideline runs almost straight and continuously along the middle of the body. The fangs are in a row. The lower jaw can be stretched out and has no barbels . The large eyes are located in or above the longitudinal axis of the body. The information on the fin formula differs depending on the author . Baruš et al. (1984) cites them as follows: dorsal II – III / 7, anals II / 6, pectorals I / 11–14, ventrals I.II / 5. The lateral scales are given as 34 to 38 (usually 36 to 37).
Another special feature of the blueband rasbora is that they can make noises. These are usually one to three seconds long, cracking sounds that can be heard over a few meters in rapid succession. These are mainly given at night. How and why the fish produce them is not yet known.
The morphological features can vary greatly, which led to the fact that various subspecies were distinguished (see also: Etymology and systematics ).
The age of wild animals can be up to 3 years. In aquariums , the animals can live up to 5 years due to the mostly better conditions.
habitat
Blue banded rasbora are able to colonize very different habitats . So it's a ubiquist . This is already evident from the large area of occurrence, the different habitats in which the species has been identified, and the ability to adapt. Bluebirds can live from small bodies of water in flooded areas to lakes , canals , reservoirs and reservoirs , former sand pits , fish ponds and other anthropogenic bodies of water such as Areks (open water channels in large cities) to large rivers such as the Danube . It is assumed that in areas that have not been shaped by humans, bluebirds occur primarily in stagnant waters of the lowlands with direct or temporary (e.g. during floods) connection to rivers. As a rule, they avoid fast currents, but can still traverse them. Furthermore, they seem to prefer eutrophic waters with little visibility and lots of vegetation. There they can form large populations and thereby massively impair the water quality. Submerged macrophytes are then negatively influenced by an increased productivity of zooplankton . This leads to large fluctuations in the pH value and the oxygen content .
distribution
The blueband harlequin originally comes from Asia and was probably unintentionally introduced to Romania from there (from the lower Yangtze ) together with grass carp ( Ctenopharyngodon idella ) and other economically interesting species in the 1960s . At first it spread mainly in the catchment area of the Danube upstream. In 1970 there were first records from Hungary , in 1982 blue banded barbels were first found in Austria . It is particularly easily introduced into fish ponds with other species as part of stocking measures. If these are drained, the little bluebirds often manage to escape and get into natural waters. The first evidence for Germany was in the White Elster near Wünschendorf in September 1984. In addition to adult animals, a young animal was caught there, which suggests a reproduction. A few years later, various authors reported evidence in Lower Saxony or the Rhine , so it can be assumed that the species was already quite widespread, especially in southern Germany at that time. In 1994 the blue-banded harlequin could also be detected in Lake Neusiedl , where it reproduces en masse. Apparently the finds in Europe are limited to large ponds used for fishing. Evidence in natural waters could often not be repeated.
Due to the widespread distribution by humans, today's native ( autochthonous ) area can hardly be reconstructed. It is believed that the type of original Taiwan to the Amur -Mündung and about between 23 and 53 latitude and in the east-west distance of between 100 ° and 140 ° east longitude occurred. Common sites include Japan , the People's Republic of China , Korea , Russia and Taiwan . This large area and the associated climatic differences illustrate the species' potential for adaptation. This enabled them to establish themselves in other regions of the world. This also promotes the emergence of subspecies. The occurrence of blueband harlequin in Kazakhstan or Uzbekistan are already considered alien ( allochthonous ). The species is absent in mainland Central Asia.
The enormous dispersal potential of the species is attributed to various factors: good adaptability, rapid reproduction (up to three generations in one summer), good development in eutrophic waters, favorable physique to cope with running waters, sticky and therefore easily transportable spawn and the small ones inconspicuous shape of the species that ensures that it is often overlooked and then, for example, taken to water bodies with other fish species.
The blue-banded harlequin was added to the “List of Unwanted Species” for the European Union in 2016.
see also: Biological Invasion , Neobiota .
food
Blue banded barbels are coarse fish living in shoals and feed mainly on small animals such as insects or juvenile fish, as well as fish eggs. They mainly live on zooplankton. The intake of larger food is not possible even through the small mouth opening. If there is a lack of food, algae coverings are also grazed.
Reproduction and development
Blue banded rasbora have a high reproductive rate. The animals, which can be up to three years old, usually become sexually mature in the first year. During the breeding season the males take on a bluish gray color and can develop relatively large spawning rashes around the mouth. The spawning season is from March to June. Habitats with a lot of vegetation and no or very little current are preferred. The females can spawn up to three (rarely four) times in a year. The males clean the relevant underground, for example stones or plants, before laying their eggs. Then the female sticks the eggs in chains of up to 340 eggs in these places. The spawning release takes place in 3 to 4 portions. The individual eggs are slightly elliptical and up to 2 mm in size. After laying eggs, the male guards them until they hatch. This takes place after 6 to 8 days (at 20 ° C) depending on the temperature. On the second day after hatching, the fry start swimming and eating on their own. They are then about 7 mm tall. They grow the most in the first month of life. During this time they reach a size of 20 to 26 mm (males).
Etymology and systematics
The generic name Pseudorasbora translates as false Rasbora . Rasbora, on the other hand, is the name given by the Hindus to the species typical of the genus. The specific epithet parva can be translated as small .
In addition to the German name Blaubandbärbling there are a number of other names. For example, pseudo-wedge barbel, amur barbel, pseudorasbora, colorful gudgeon or Asian gudgeon were used.
Due to the variability in the external characteristics, various subspecies were distinguished:
- P. p. altipinna Nichols, 1925
- P. p. depressirostris Nichols, 1925
- P. p. parvula Nichols, 1929
- P. p. tenuis Nichols, 1929
- P. p. fowleri Nichols, 1925
- P. p. monstrous nichols, 1925
- P. p. parva Nichols.
However, these are not universally accepted. Later studies showed that it could also be a variant of this polymorphic species. A clarification of this problem is still pending.
meaning
Due to their spreading potential, the negative influence of the blue banded harlequin on the native flora and fauna should be mentioned. By changing the water quality and as a food and habitat competitor for fish with similar demands, they can become dangerous to native species and thus contribute to a species impoverishment of the waters. In addition, they are often favored by the lack of specific parasites or predators . However, detailed studies are not yet available.
As food fish , blue banded barbels are less suitable in Central Europe due to their small size. In other regions of the world, however, small fish are also prepared and consumed. However, this type of use is insignificant. In contrast, its use as animal feed could be more important. Blueband barbels are well suited either as feed fish for fish farms or as bait fish for anglers . Due to the lack of nature conservation regulations or the resulting restrictions, this use is recommended. It should be noted, however, that such use can contribute to further spread with the corresponding negative consequences.
Blue banded barbels are very suitable for keeping in an aquarium. With their modesty and adaptability, they offer good conditions for producing offspring. However, they are not very conspicuous in terms of color and therefore not very significant.
You can buy blueband barbels in Germany as food, aquarium and bait fish in stores.
literature
- Andreas Arnold: Naturalized fish species. The Neue Brehm Library 602 . Ziemsen Verlag, Wittenberg 1990, ISBN 3-7403-0236-4 .
- Maurice Kottelat & Jörg Freyhof: Handbook of European Freshwater Fishes . Publications Kottelat, Cornol (Switzerland) 2007, ISBN 978-2-8399-0298-4 .
Web links
- Blueband on Fishbase.org (English)
- Blueband: more information and photos
- Pseudorasbora parva inthe IUCN 2013 Red List of Threatened Species . Posted by: Huckstorf, V., 2010. Retrieved December 16, 2013.
Individual evidence
- ↑ List of Invasive Alien Species of Union Concern (PDF) accessed on July 15, 2016