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Pseudotropheus demasoni Konings, 1994
![Pseudotropheus demasoni young wild female from Pombo Ricks, Lake Malawi [Tanzania], mouth-brooding in the aquarium [France]. Fortunately, this species breeds easily in the aquarium and is now widely reared, what will help reducing the fishing pressure on this restricted-range species with low population density](../gallery/thumbs/p07901t.jpg){kind=small}
![Pseudotropheus demasoni males displaying at Ndumbi Point, lake Malawi [Tanzania]](../gallery/thumbs/p06422t.jpg)
![Pseudotropheus demasoni wild pair (male in front) from Pombo Rocks, Lake Malawi [Tanzania], in the aquarium [France]. Despite its very small size, Pseudotropheus demasoni is incredibly aggressive with its congeners, and even in large tanks (500 l), groups often end in only one individual or, if the owner is lucky, one pair](../gallery/thumbs/p07900t.jpg){kind=small}
![Pseudotropheus demasoni wild male from Pombo Rocks, Lake Malawi [Tanzania], in the aquarium [France]. Well-fed in the aquarium, wild individuals reach a much larger size than in the natural habitat](../gallery/thumbs/p07898t.jpg){kind=small}
![Pseudotropheus demasoni wild female from Pombo Rocks, Lake Malawi [Tanzania], in the aquarium [France]](../gallery/thumbs/p07899t.jpg){kind=small}
最初描述为 Pseudotropheus demasoni:
- Konings, Ad. 1994. "Pseudotropheus demasoni sp. nov: a sexually monomorphic cichlid from the Tanzanian coast of Lake Malawi". The Cichlids Yearbooks. v. 4, pp. 24-27 (crc00173) (摘要).
分类史:
- Pseudotropheus demasoni, Konings, 1994, 最初的组合.
分组:
- 栖息地: Lakes: sediment-free rocky (Konings, 1994).
- 摄食: Algae pickers (Konings, 1994).
- 形态: Dwarf cichlids (Konings, 1994).
- 水族箱: Intermediate aquarists (Konings, 2007).
- Breeding: Maternal mouthbrooder (Konings, 2007).
- Special: Mbuna (Fryer et al, 1972).
词源: This species is named in honor of Laif DeMason (Homestead, Florida) without whom the author's preliminary survey of the Tanzanian waters of Lake Malawi could not have been completed. Laif DeMason, importer, exporter, and breeder of cichlids, has greatly stimulated the keeping of cichlids in the USA.
鉴别: A small species of the genus Pseudotropheus with a unique coloration in females: blue-black bars on a light blue background. The color pattern of males and immature individuals is indistinguishable from that of females. The species resembles P. saulosi (males only) in coloration and size but differs in having only four dark bars below the dorsal fin whereas P. saulosi males have five or six. Moreover female and immature P. saulosi have a bright yellow-orange color. Other species with four bars below the dorsal (P. livingstonii, Tropheops microstoma, Metriaclima lombardoi, M. lanisticola, and Labidochromis zebroides) are easily distinguished from P. demasoni on the basis of obvious differences in morphology or coloration. L. zebroides has unicuspid teeth whereas the teeth of P. demasoni are bicuspid or tricuspid. P. livingstonii and M. lanisticola do not exhibit the dark blue coloration seen in P. demasoni. The mouth of T. microstoma is placed in a ventro-terminal position whereas that of P. demasoni is terminal. M. lombardoi females exhibit a much lighter blue color and lack the blue-black color seen in the lower fins of P. demasoni.
尺寸: Males in the wild rarely get larger than 8 cm total length while females are somewhat smaller at about 6.5 cm TL. In the aquarium males can attain a total length of about 10 cm.
性二型: As one of the few blue-colored mbuna, male and female Pseudotropheus demasoni are indistinguishable in coloration.
俗名: Demasoni.
标本产地: Pombo Rocks, Lake Malawi, Tanzania.
分布: Pseudotropheus demasoni was described from Pombo Rocks but was also found at nearby Ndumbi Point. Pombo Rocks is approximately 15 km south of the Ruhuhu River delta. The reef may be the exposed part of a much larger rocky offshore area most of which is now covered by sand and sediment. The rocky reef was circumnavigated during SCUBA diving and appeared not to extend beyond the shallows (maximum depth approximately 7 meters).
栖息地国家: 坦桑尼亚.
原栖息地: Pseudotropheus demasoni inhabits the upper three to four meters of the rocky habitat. It was seen regularly but almost all sightings involved solitary individuals. It seems that this species is evenly spread throughout the habitat, each individual having a feeding area about two meters in diameter. Such feeding areas normally include a large rock or the upper face of a boulder. P. demasoni is generally ignored by other species, but chased from some areas occupied by breeding males of more boisterous species. The occupation of such relatively large feeding areas may imply that suitable food is not abundant and one might expect fierce competition to exist among conspecifics, resulting in aggressive behavior towards their own kind. In the event two or three individuals were found close together, no hint of intraspecific aggression was noted. In fact P. demasoni behaved remarkably peacefully towards all species including its own. Therefore it is so surprising that it behaves very aggressively towards conspecifics in the aquarium.
产地: Ndumbi Point (坦桑尼亚, native), Pombo Rocks (坦桑尼亚, native).
摄食: Pseudotropheus demasoni feeds on algae attached to rocks. It bites the algal strands from the substrate, and feeding sites seem to be visually selected (as is the case with most herbivorous Labidochromis). Representatives of the genus Labidochromis are rare at Pombo Rocks, and only a few individuals of one species, L. sp. 'gigas pombo', were found. It may be that P. demasoni occupies the niche normally filled by herbivorous Labidochromis at other rocky sites, i.e. it selects small pockets of algae which are inaccessible to other mbuna (e.g. algae growing in tiny cracks which are too narrow for larger cichlids to reach into). The relatively long gut in one specimen (205% of standard length) suggests a high percentage of vegetable material in the diet (Konings, 1994).
繁殖: Breeding or sexually territorial individuals were not found in the lake, but mouth-brooding females do not hide as much as one expects for the small size of the fish. The fact that one female with a standard length of 42.5 mm had ripe eggs in her ovary suggests that Ps. demasoni matures at a very small size. In the aquarium males do have particular areas that they defend as a spawning territory but only when spawning is imminent. In the wild spawning probably happens on the spot when a ripe female is courted by an adult male. In the aquarium it takes almost three weeks before the fry are released by the female. Broods are rarely larger than 10 eggs.
水族行业: Pseudotropheus demasoni are among the smallest cichlids from Lake Malawi and can be kept together with any other Malawian cichlid provided they are not regarded as food by other tank-mates. In captivity, P. demasoni that are normally non-territorial in the lake, become territorial. Males defend a small territory from which mainly conspecifics are chased. In a community tank several conspecific males can be kept together provided they are each given an opportunity to occupy their own cave. This means that enough shelter must be available and all the males should be introduced at the same time. In the case of most of the small mbuna it is recommended that several males are kept in the same tank (which should be large enough to house these comfortably) because then the dominant male will show his best color most of the time.
Sex is not always easily determined in small individuals, but should pose no problem in adults by examining the vents. More than one female per male is, of course, advisable but a 1:1 ratio or even more males than females is possible with this species. A breeding tank for Pseudotropheus demasoni can be as small as 150 liters. It is recommended that the pH of the aquarium water be maintained between 7.0 and 8.5 and to keep the temperature constant at a value between 23 and 28° C.
保育: Pseudotropheus demasoni 由国际自然保护联盟（IUCN）在濒危物种红色名录中为自然保育而进行了评估 evaluated (VU) 易危（Vulnerable） (2006). The extremely narrow distribution of P. demasoni makes it very vulnerable to overfishing by ornamental fish collectors. 12 years after its discovery I was pleased to still see this small mbuna at Pombo Rocks and it appears that its population is stable for the moment. Its enormous popularity has led to massive breeding by the larger fish farms so that we don't need to exploit the natural population.
意见: Pombo Rocks, a shallow rocky reef about 15 km south of the Ruhuhu River delta, is inhabited by many different rock-dwelling cichlid species, several of which are not found at any other location along the Tanzanian coast. As well as the few allegedly endemic species some geographical variation in other species was noted. Although it is obvious that the Ruhuhu River delta forms an impassable barrier to the northward spread of the cichlids at Pombo Rocks, to the south the reef is separated from the rocks at Lundu by a sandy beach a mere 6 km in length. Nevertheless the communities at Pombo Rocks and Lundu differ considerably. Pseudotropheus demasoni was discovered in 1993 by Jackson Nunda, a collector who worked for Laif DeMason's export station (Lake Nyasa African Fishes—LANYAFI) in Mbeya, Tanzania. He accompanied Andreas Spreinat on a survey tour along the Tanzanian coast. Two days after the discovery Laif collected some at Pombo Rocks to bring back to his fish farm in Florida and sent me the specimens that didn't make the transport. I used these to describe the species.
参考文献:
- Konings, Ad. 1994. "Pseudotropheus demasoni sp. nov: a sexually monomorphic cichlid from the Tanzanian coast of Lake Malawi". The Cichlids Yearbooks. v. 4, pp. 24-27 (crc00173) (摘要).
- Konings, Ad. 2007. "Malawi cichlids in their natural habitat (4th edition)". Cichlid Press (crc01558).
- Spreinat, Andreas. 1994. "Malawisee-Cichliden aus Tansania". Unitext Verlag, Bovenden, Germany (crc01773).
引语:
Konings, Ad. (五月 13, 2011). "Pseudotropheus demasoni Konings, 1994". CichlidRoomCompanion网站. 检索 五月 19, 2013, 从: http://www.cichlidae.com/gallery/species.php?id=528&content=profile&lang=cn.
