| Perissodus | |
|---|---|
 | |
| Perissodus microlepis | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cichliformes |
| Family: | Cichlidae |
| Tribe: | Perissodini |
| Genus: | Perissodus Boulenger, 1898 |
| Type species | |
| Perissodus microlepis Boulenger, 1898 | |
Perissodus is a genus of cichlids endemic to Lake Tanganyika in Africa. They feed on scales. [1]
There are currently two recognized species in this genus: [2]
In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches. Starting with a single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits. The prototypical example of adaptive radiation is finch speciation on the Galapagos, but examples are known from around the world.
Cichlids are fish from the family Cichlidae in the order Cichliformes. Traditionally Cichlids were classed in a suborder, the Labroidei, along with the wrasses (Labridae), in the order Perciformes, but molecular studies have contradicted this grouping. On the basis of fossil evidence, it first appeared in Tanzania during the Eocene epoch, about 46–45 million years ago. The closest living relative of cichlids is probably the convict blenny, and both families are classified in the 5th edition of Fishes of the World as the two families in the Cichliformes, part of the subseries Ovalentaria. This family is large, diverse, and widely dispersed. At least 1,650 species have been scientifically described, making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000.
Symphysodon is a genus of cichlids native to the Amazon river basin in South America. Due to their distinctive shape, calm behavior, many bright colors and patterns, and dedicated parenting techniques, discus are popular as freshwater aquarium fish, and their aquaculture in several countries in Asia is a major industry. They are sometimes referred to as pompadour fish. The discus fish has attracted a cult following of collectors and has created a multimillion dollar international industry complete with shows, competitions, and reputable online breeders.
Lake Tanganyika is an African Great Lake. It is the second-oldest freshwater lake in the world, the second-largest by volume, and the second-deepest, in all cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. The lake is shared among four countries—Tanzania, the Democratic Republic of the Congo (DRC), Burundi, and Zambia, with Tanzania (46%) and DRC (40%) possessing the majority of the lake. It drains into the Congo River system and ultimately into the Atlantic Ocean.
Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a variety of different animals, such as the Darwin's frog, fish are by far the most diverse mouthbrooders. Mouthbrooding has evolved independently in several different families of fish.
Tropheus is a small genus of at least six species of cichlids endemic to Lake Tanganyika in East Africa. The genus is widespread across all regions of Lake Tanganyika, from Burundi in the north to Zambia in the south. Males and females are relatively similar in color, with only subtle sexual dimorphism in the form of the male's larger size. All species are maternal mouthbrooders, with the females caring for their eggs and fry in their mouths; this characteristic provides their generic name, Tropheus, which comes from the Greek trophos, which means "to nurse" or, according to Boulenger, "one who rears, brings up, educates". The genus is fished lightly by the local population, but has never become a staple food fish due to its relatively small size and its habitat, which enables it to dart between rocks when threatened.
Corematodus is a small genus of haplochromine cichlids native to the Lake Malawi basin in Africa. They feed on scales and fins of other cichlids.
Docimodus is a small genus of cichlids native to east Africa where they are found in Lake Malawi and one species (D. johnstoni) also occurs in Lake Malombe and the upper Shire River.
Paedophagy in its general form is the feeding behaviour of fish or other animals whose diet is partially, or primarily the eggs or larvae of other animals. However, P. H. Greenwood, who was the first to describe paedophagia, defines it to be a feeding behaviour evolved among cichlid fishes.
Lepidophagy is a specialised feeding behaviour in fish that involves eating the scales of other fish. Lepidophagy is widespread, having evolved independently in at least five freshwater families and seven marine families. A related feeding behavior among fish is pterygophagy: feeding on the fins of other fish.
Perissodus microlepis is a species of cichlid endemic to Lake Tanganyika. This species reaches a length of 11 centimetres (4.3 in) TL. This species can also be found in the aquarium trade. It is a scale-eating 'parasite' on other fish species. It occurs in two distinct morphological forms. One morph has mouth parts twisted to the left, enabling it to eat scales off its victim's right flank. In contrast, the other morph, whose mouth is twisted to the right, eats scales off its victim's left flank. The relative abundance of the two morphs in populations is regulated by frequency-dependent selection.
Plecodus elaviae is a species of cichlid endemic to Lake Tanganyika. This schooling species is a scale-eater, plucking scales from other fishes. Both parents care for the offspring in this mouthbrooder. This fish can reach a length of 32 centimetres (13 in) TL.
Plecodus is a genus of cichlids endemic to Lake Tanganyika in Africa. They feed on scales.
Plecodus straeleni is a species of cichlid fish that is endemic to Lake Tanganyika in East Africa. This species can reach a total length of 16 centimetres (6.3 in).
Xenochromis hecqui is a species of cichlid endemic to Lake Tanganyika in East Africa. It is mainly found at depths of 6–100 m (20–328 ft), but has been recorded somewhat deeper, even in waters virtually devoid of oxygen. This species is a scale eater, consuming the scales off of other fishes, but will also feed on copepods. It can reach a total length of up to 30 cm (12 in). Currently it is the only known member of its genus. The specific name honours the Belgian Lieutenant Célestin Hecq (1859-1910), a member of the Belgian colonial forces fighting the slave trade who collected the type of this species.
Perissodini is a tribe of African cichlids, containing three genera of freshwater fish found only in Lake Tanganyika.
Sargochromis is a genus of haplochromine cichlids native to freshwater habitats in Southern Africa, where found in the upper and middle Zambezi basin, Okavango delta, Cunene basin, Cuvelai basin and southeastern Congo Basin. They are typically known as happies or smallmouths. The latter name refers to their small mouth compared to their close relatives, the largemouths of the genus Serranochromis. Unlike the species in that genus which mostly feed on other fish, Sargochromis mostly feed on invertebrates, but in some species plant material is important. On occasion they will also eat small fish, and the stomachs of S. carlottae and S. codringtonii commonly contain fish scales, but whether these are already-lost scales that are picked off the bottom or they are actively bumped off large fish is unknown. Some of the species that feed heavily on aquatic snails have been used for biological pest control. Sargochromis are mouthbrooders. Depending on the exact species, they reach a maximum total length of 20 to 48 cm (8–19 in).
Most bony fishes have two sets of jaws made mainly of bone. The primary oral jaws open and close the mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. The oral jaws are used to capture and manipulate prey by biting and crushing. The pharyngeal jaws, so-called because they are positioned within the pharynx, are used to further process the food and move it from the mouth to the stomach.
Xenotilapia rotundiventralis is a species of cichlid endemic to the African Great Lake Lake Tanganyika where it occurs in the southern and southeastern parts of the lake. It is found in shallow areas with a mainly sandy substrate interspersed with rocks. It forms schools which can number more than one thousand individuals. It feeds exclusively on plankton by picking out individual food items with their protractile mouths. Both sexes mouthbrood although up to 6 mm (0.24 in) in length, the fry are mouthbrooded only by the female. If the young are separated from their parents they can be found among other cichlid broods e.g. Lepidiolamprologus elongatus and Perissodus microlepis. Some authorities consider this species to be in a separate genus, Microdontochromis.
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