Marbled hatchetfish
| Marbled hatchetfish | ||||||||||||
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Marbled hatchet belly |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Carnegiella strigata | ||||||||||||
| ( Günther , 1864) |
The marbled hatchet-bellied fish ( Carnegiella strigata ) is a freshwater fish from tropical South America belonging to the tetras .
features
It reaches a length of around four centimeters and shows a body shape that is typical of hatchet-bellied tetra and is adapted to life just below the surface of the water: a laterally flattened body with an almost horizontally running back profile and clearly arched belly line as well as a strongly upper mouth as a specialization of the acquisition of food on the Water surface.
The back is dark olive green. Underneath, from the gill cover to the upper section of the tail root, runs a gold to silvery shimmering line. Three to four irregularly jagged dark brown to black bandages pattern the belly. The striking marble pattern distinguishes Carnegielle strigata from all other types of hatchet, which are more or less monochrome, silvery. It shares with the other species of the genus Carnegiella the lack of adipose fin .
- Fin formula : dorsal 10–11, anal 25–28.
- Scale formula : mLR 27–32.
distribution
Carnegiella strigata has a relatively large distribution area, over the entire Amazon basin , the catchment areas of the southern tributaries of the Amazon and the Río Caquetá . It thus extends over the states of Brazil , Peru , Colombia and the Guiana countries .
Depending on the place where it was found, the marble-like color pattern can be between strongly contrasting and blurred. Regional differences can also occur with other color characteristics. Specimens from the Igarapé Sacado (western Brazil) differ, for example, from specimens from other localities in addition to a particularly strong, sloping backward-sloping abdominal band and an almost pigment-free region around the pectoral fin or the area between the eye and the abdominal region, in addition, by a striking blue sheen and red coloration upper Irish half .
Way of life
Because of its wide distribution, the habitats of Carnegiella strigata are quite different. It lives in brooks that run through open marshland, in heavily shaded primary rainforest brooks or in lake-like, current-free waters of extensive floodplains. The water color ranges from clear and slightly yellowish ( clear water ) to deep dark brown ( black water ). Due to the different types of water and light conditions, the habitat can have both lush underwater vegetation and be completely free of plants.
Despite these differences, the waters inhabited by Carnegiella strigata are similar in terms of their chemical parameters. Measurements at the sites show that they are predominantly very soft ( KH and GH <1 ° dH), acidic to very acidic ( pH value between 4.9 and 6.7) and low in salt ( electrical conductivity <30 µS / cm) . The water temperature is usually between 24 and 27 ° C, in the northern distribution area also at 19 ° C.
The way of life is also very similar regardless of the different habitats. They live socially and peacefully in large groups on the open water surface, often at water levels of 0.5 to 1 m, and hunt small insects that have fallen into the water as well as aquatic insect larvae. They are always at the edge of the water near the bank, so that in the event of danger they can quickly seek shelter in the dense bank vegetation consisting of aquatic or marsh plants or between branches, twigs and leaves of the dead wood lying in the water . When fleeing from predatory fish , such as the pike tetras of the genus Boulengerella , they often shoot above the surface of the water to escape them.
In their habitat they often live in close proximity to other small tetras such as Hyphessobrycon eques or Pyrrhulina brevis , cichlids of the genus Apistogramma and catfish of the genus Corydoras and the family Loricariidae . In the distribution area of Carnegiella marthae , Carnegiella strigata occasionally forms mixed groups with these.
Systematics
The Marbled Beilbauchfisch was the German zoologist 1864 Albert Günther under the name Gasteropelecus strigatus described and later the genus Carnegiella assigned. Carnegiella strigata is probably a swarm of very closely related and externally indistinguishable species. The smaller Black Swing Beilbauchfisch ( Carnegiella marthae ) is phylogenetically within the C. strigata -Artenschwarms and is closer to the in northwestern Brazil at Barcelos occurring C. strigata related -Population than this z. B. with the C. strigata population found in the western state of Acre . This makes C. strigata a paraphyletic group that will have to be divided into several species in the future.
Aquaristics
attitude
Carnegiella strigata was first introduced in Germany in 1912 and is the first and to this day most commonly imported hatchet-bellied tetra species. Practically only wild-caught fish can be found in trade, as commercial reproduction has not yet been successful. Specimens of Carnegiella marthae are more often in the trade as bycatch , which laypeople and dealers often do not immediately recognize as a separate species under Carnegiella strigata .
Since Carnegiella strigata is sociable, it should be kept in groups of at least five individuals in aquariums with a length of 70 cm or more. The swimming and protection needs of the animals should be taken into account by keeping large parts of the water surface free, but the marginal zones on the water surface offer sufficient protection options through aquatic plants, land plants protruding into the water or roots. The pool should also not be open, as the animals are good jumpers. The height of a cover should be high enough so that the hatchet bellies do not injure themselves on equipment mounted in the cover when jumping.
Carnegiella strigata are not picky about their nutritional requirements and, after getting used to them, also accept dry food . Living, frozen or freeze-dried mosquito larvae , water fleas etc. and especially living, flightless mutations of the fruit fly Drosophila melanogaster correspond more to the natural food supply and should at least be fed as a supplement.
Deviating from the water values in the natural habitat, it can also be successfully maintained in slightly alkaline (pH up to 7.5) and medium-hard water (up to 14 ° dGH).
Reproduction and breeding
In the real sense of the word, breeding has not yet been successful for any species of hatchet-bellied tetra. A more or less spontaneous reproduction of Carnegiella strigata (as well as of Gasteropelecus sternicla ) could already be observed in a few cases.
The decisive problem with targeted breeding seems to be the formation of a spawning base , which is probably due to the lack of nutrition necessary for the development of sex products. Reduced physical condition due to the common disease or treatment against ichthyophthiriosis can also have a negative impact on the suitability of breeding animals. Water values that come as close as possible to those at natural sites appear to be beneficial for successful reproduction, but not decisive.
The most promising approach to breeding so far is the attempt to encourage the formation of a spawning base by feeding black mosquito larvae and fruit flies abundantly. Once this has formed, spawning can take place in soft, acidic, possibly peat-filtered water and in subdued light.
During courtship the animals are extremely active and shoot around wildly on the surface. During each pairing , the fish press against each other and lay two to five eggs under the surface of the water. These sink to the ground or get stuck in delicate plants or roots of floating plants. The fry hatch after 30-36 hours, swim freely after five days and develop their typical body shape after about 20 days.
swell
literature
- Wolfgang Staeck: Tetra from South America. Verlag Dähne 2008, ISBN 3-935175-41-8 .
- Günther Sterba : The world's freshwater fish. 2nd Edition. Urania, Leipzig / Jena / Berlin 1990, ISBN 3-332-00109-4 .
- Hans A. Baensch : Aquarien Atlas 1. Verlag Mergus 2006, paperback edition, ISBN 3-88244-227-1 .
- Helmut Pinter: Handbuch der Aquarienfischzucht , Verlag Eugen Ulmer, 1998, ISBN 3-8001-7391-3 .
Individual evidence
- ↑ Kelly T. Abe, Tatiane C. Mariguela, Gleisy S. Avelino, Ricardo MC Castro, Claudio Oliveira: Multilocus molecular phylogeny of Gasteropelecidae (Ostariophysi: Characiformes) reveals the existence of an unsuspected diversity. Molecular Phylogenetics and Evolution, July 2013, doi: 10.1016 / j.ympev.2013.07.005
