Hardheaded

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Hardheaded
Craterocephalus eyresii

Craterocephalus eyresii

Systematics
Ovalentaria
Superordinate : Earfish relatives (Atherinomorphae)
Order : Earfish (Atheriniformes)
Family : Old world earfish (Atherinidae)
Subfamily : Craterocephalinae
Genre : Hardheaded
Scientific name
Craterocephalus
McCulloch , 1912

In the fish genus of the hard-headed fish ( Craterocephalus ), 25 described fresh or brackish water species are now placed. The genus belongs to the Old World earfish and occurs in Australasia . It is the richest in species and one of the most widespread among Australia's freshwater fish species.

features

Hard-headed fish are elongated, spindle-shaped, typically five to ten centimeters in size . The silvery fish have a split dorsal fin , pectoral fins set relatively high on the sides, a thin, silvery central longitudinal stripe and no side line.

Occurrence

Hartköpfchen inhabit lakes and rivers in the interior of Australia and New Guinea (19 species) to the coastal area (5 species). One species lives in the far east of Timor .

Some species only occur in a very limited area. The species found in freshwater inhabit different habitats, u. a. Streams in high-lying rainforests, cloudy lowland rivers as well as warm springs and periodically flowing waters in arid areas. C. cuneiceps and C. eyresii tolerate salinities of up to 70 and 100 ‰, respectively, while C. dalhousiensis was found at water temperatures around 41 ° C.

Way of life and reproduction

Hard heads come in groups. The fish are omnivores and in nature mainly eat small invertebrates , algae and fish eggs . Life expectancy in nature is estimated at two to three years.

Sexual maturity occurs around three to four centimeters in length at the end of the first year of life. They spawn in pairs on the ground in underwater vegetation all year round (most intensely in spring and summer with up to 85 eggs per day). The eggs, which are one to two millimeters in size, have adhesive threads so that they stick there. The larvae hatch after one to two weeks.

use

Craterocephalus stercusmuscarum and Craterocephalus stramineus are of little importance as aquarium fish in Australia. In New Guinea, the local population occasionally uses the hard-headed fish as food.

Systematics

The species Sashatherina giganteus , described in 2011 from Lake Lakamora in the south of the province of Papua , is considered to be the closest relative of the species from the genus Craterocephalus .

The genus Craterocephalus contains 25 species, which are divided into five phylogenetic groups.

The freshwater species probably have ancestors of marine origin who lived in inland salt water and then gradually adapted to freshwater habitats. According to comparative genetic studies, the most original of the freshwater species are the group with C. honoriae and C. mugiloides .

Species from Australia :

Species from New Guinea , south of the Massif Central:

Species from East Timor :

Individual evidence

  1. ↑ W. Ivantsoff, GR Allen, 2011: A new species and genus of a large and unusual freshwater hardyhead, Sashatherina giganteus (Pisces: Atherinidae) from West Papua, Indonesia and a comparison with its closest relatives of the genus Craterocephalus . Aqua, International journal of ichthyology, 17 (1): 43-57.
  2. ↑ P. Unmack & T. Dowling: Biogeography of the genus Craterocephalus (Teleostei: Atherinidae) in Australia . In: Molecular Phylogenetics and Evolution . tape 55 , no. 3 , 2010, p. 968-984 .
  3. ^ H. Larson, W. Ivantsoff & L. Crowley: Description of a new species of freshwater hardyhead, Craterocephalus laisapi (Pisces: Atherinidae) from East Timor . In: aqua International Journal of Ichthyology . tape 10 , no. 2 , 2005, ISSN  0945-9871 , p. 81-88 .

literature

  • G. Allen, S. Midgley, M. Allen: Field Guide to the Freshwater Fishes of Australia . 2nd Edition. Western Australian Museum, Perth 2003, ISBN 0-7307-5486-3 .
  • Harro Hieronimus: Rainbow Fish and Kindred Families . ACS, Mörfelden-Walldorf 2002, ISBN 3-931702-80-4 .

Web links