Pachypanchax varatraza

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Pachypanchax varatraza
Systematics
Superordinate : Earfish relatives (Atherinomorphae)
Order : Toothpies (Cyprinodontiformes)
Subordination : Aplocheiloidei
Family : Aplocheilidae
Genre : Pachypanchax
Type : Pachypanchax varatraza
Scientific name
Pachypanchax varatraza
Loiselle , 2006

Pachypanchax varatraza ( Malagasy Varatraza - east wind) is an endangered fish in Madagascar . Its name alludes to the unexpected presence of the species on the eastern slopes of the Tsaratanana massif .

distribution and habitat

The freshwater fish inhabited by rainforest shaded, vegetation-poor rivers in the river areas of the Menambery , Fanambana and Ampanobe in northeast Madagascar. Its native waters are weakly acidic , relatively soft and have only a low conductivity .

Appearance

The robust fish can reach a standard length of eight centimeters and is thus one of the larger representatives of the genus Pachypanchax . Its appearance corresponds to the typical habitus of this group. The dorsal fin standing far back begins above the attachment of the ninth and tenth rays of the anal fin . It has a pattern of small dots in the back third. Starting from the fin attachment, the first two thirds of the caudal fin also show a pattern of fine dark points. The pectoral fins are about 13.4 percent of standard length, the smallest in the relationship among the Pachypanchax species. The first gill arch carries ten to twelve gill trap processes. There is a green and a red color form, only expressed in the male animals. The scales of the green variant show rusty to chestnut brown corners in the back half of the body, their size and intensity depending on the population. The drawing of female individuals is less pronounced than that of their male counterparts. P. varatraza has 30 to 32 scales along the sideline (SL).

Fin formula :

  • Dorsal II-IV / 8-11
  • Anal II-III / 14-17
  • Pectorals 14-16
  • Ventral I / 5

Way of life

P. varatraza finds its food both on the surface of the water and on the bottom of the water. It feeds mainly on approach food and insect and insect larvae living in the water. The Madagascar dwarf fisherman ( Alcedo vintsioides ) and a large goby , Glossogobius giuris , are probably chasing him . The reproductive phase is probably quite extensive and lasts the entire rainy season.

status

In several parts of its original range, the populations of P. varatraza have now died out. The snakehead fish Channa maculata, introduced in Madagascar in 1978, poses a major threat . This neozoon has already wiped out the native species in the lower reaches of Menambery, Fanambana and Ampanobe. The destruction of the rainforest causes considerable problems; due to the associated disruption of the water balance, many tributaries of the Menambery no longer carry water all year round and are therefore unsuitable for living space. The Fanambana catchment area has not yet been affected to the same extent by deforestation, which is why the loss of habitat is less pronounced here . The water supply of the Ampanobe is stable due to less seasonal rainfall and relatively intact forest cover. An introduced species of gambus , Gambusia holbrooki , in its middle and upper reaches, however, gives cause for concern, as it exerts a high feeding pressure on fish fry. The IUCN lists P. varatraza as endangered ("endangered").

swell

literature

  • Paul V. Loiselle: A review of the Malagasy Pachypanchax (Teleostei: Cyprinodontiformes, Aplocheilidae), with descriptions of four new species. Magnolia Press, 2006 ( Download , eng., PDF; 676 kB)

Individual evidence

  1. ↑ Channa maculata (Lacepde, 1802) Blotched Snakehead ( English ) Florida Integrated Science Center. Archived from the original on May 14, 2008. Retrieved May 11, 2010.

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