Craterocephalus
In the genus of fish of the hard heads ( Craterocephalus ) today 25 described freshwater or brackish water -dwelling species are provided. The genus belongs to the Old World ears fish and is found in Australasia. She is among Australia's freshwater fish species, the richest and one of the most widespread.
Features
Hart heads are elongated, spindle-shaped, typically five to ten centimeters large fish. The silvery little fish have a divided dorsal fin relatively high set at the sides of the pectoral fins, a thin silvery median longitudinal stripes and no lateral line.
Occurrence
Hart heads 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 Timor.
Some species occur only in a very limited area. The occurring in freshwater species inhabit different habitats, including Streams in hochgelegenem rainforest, turbid lowland rivers and hot springs and periodically flowing water in arid areas. C. cuneiceps and C. eyresii tolerate salinities up to 70 or 100 ‰, while C. dalhousiensis was encountered at water temperatures of 41 ° C.
Life and reproduction
Hart heads found in clusters. The fish are omnivorous and eat in nature mainly small invertebrates, algae and fish eggs. The life expectancy in nature is estimated to be two to three years.
Sexual maturity occurs at about three to four centimeters in length at the end of the first year of life. They spawn throughout the year ( most intense in spring and summer with up to 85 eggs per day) pairs on the ground in underwater vegetation from. The one to two millimeters large eggs have adhesive threads, so that they remain adhered thereto. The larvae hatch after one to two weeks.
Use
Craterocephalus stercusmuscarum and Craterocephalus stramineus are of little importance as an aquarium fish in Australia. In New Guinea, the hard head of the population are locally occasionally used as a food fish.
System
In the genus Craterocephalus 25 species are summarized which are divided into five phylogenetic groups.
The living in freshwater species probably have ancestors of marine origin, who lived in inland salt water and then successively adapting to freshwater habitats. The most original of the freshwater species are for comparative genetic studies, the group with C. honoriae and C. mugiloides.
Species from Australia:
- Craterocephalus amniculus Crowley & Ivantsoff, 1990
- Craterocephalus Capreoli Rendahl, 1922
- Craterocephalus centralis Crowley & Ivantsoff, 1990
- Craterocephalus cuneiceps Whitley, 1944
- Craterocephalus dalhousiensis Ivantsoff & Glover, 1974
- Craterocephalus eyresii ( Steindachner, 1884)
- Craterocephalus fluviatilis McCulloch, 1913
- Craterocephalus gloveri Crowley & Ivantsoff, 1990
- Craterocephalus helenae Ivantsoff, Crowley & Allen, 1987
- Craterocephalus honoriae Ogilby, 1912
- Craterocephalus lentiginosus Ivantsoff, Crowley & Allen, 1987
- Craterocephalus marianae Ivantsoff, Crowley & Allen, 1987
- Craterocephalus marjoriae Whitley, 1948
- Craterocephalus mugiloides McCulloch, 1912
- Craterocephalus munroi Crowley & Ivantsoff, 1988
- Craterocephalus pauciradiatus ( Günther, 1861)
- Craterocephalus stercusmuscarum ( Günther, 1867)
- Craterocephalus stramineus ( Whitley, 1950)
Species from New Guinea, south of the Massif Central:
- Craterocephalus fistularis Crowley, Ivantsoff & Allen, 1995
- Craterocephalus kailolae Ivantsoff, Crowley & Allen, 1987
- Craterocephalus lacustris Trewavas, 1940
- Craterocephalus nouhuysi ( Weber, 1910)
- Craterocephalus pimatuae Crowley, Ivantsoff & Allen, 1991
- Craterocephalus randi Nichols & Raven, 1934
Species from East Timor:
- Craterocephalus laisapi Larson, Ivantsoff & Crowley, 2005