Kribensis
Encyclopedia
Pelvicachromis pulcher is a freshwater
fish of the cichlid
family, endemic to Nigeria
and Cameroon
. The species is popular amongst aquarium
hobbyists, and is most commonly sold under the name kribensis
, although the species has other common names, including various derivatives of kribensis: krib, common krib and rainbow krib, along with rainbow cichlid and purple cichlid. Originally P. kribensis, its scientific name was changed to P. pulcher. is Latin
for "beautiful". The species is a popular cichlid for the aquarium.
s, the intensity of which changes during courtship
and breeding. The dorsal and caudal fins also may bear gold-ringed eye spots or ocelli. Males show colour polymorphisms
in some population
s collected at single localities. Juveniles are monomorphic
until approximately six months of age.
5.6–6.2), soft water
(12–22 mg L-1 CaCO3
). Populations of P. pulcher also occur outside its natural range in Hawaii
, USA
as a by-product of the ornamental fish trade.
The species inhabits both slow and fast-moving water, though it is only found where patches of dense vegetation are available. Other fish that share the habitat of P. pulcher include other Pelvicachromis species (Pelvicachromis taeniatus
), other cichlid species (Chromidotilapia guntheri
, Hemichromis cristatus and H. fasciatus, Tilapia mariae and T. zilli
) along with Brycinus longipinnis
and Aphyosemion
species. The species is prey for a number of rheophilic
predators including Hepsetus odoe
, Hydrocynus forskahlii
, and Lates niloticus (Nile perch
). In the natural habitat, P. pulcher have been observed excavating, defending, and sheltering in caves dug underneath plants, and these holes are also used for breeding. Not all P. pulcher, however, claim territories and many live in large, non-reproductive aggregates.
s, crustacean
s, and insect
s, analysis of the stomach contents of wild P. pulcher suggests this is incorrect. A study by Nwadiaro (1985) of 161 individuals showed that the main food items were diatom
s, green algae
, pieces of higher plants
, along with blue-green algae. Invertebrate
s, though consumed, were found to be relatively uncommon food items for wild fish.
Like other Pelvicachromis species, P. pulcher is sexually dimorphic. Males have a pointed pelvic fin, while the female's pelvic fin is more rounded in appearance. In addition, males are larger, lack the gold sheen to the dorsal fin and have a more elongated, spade-shaped caudal fin. Despite the suggestion in the aquarium literature that the species forms monogamous pairs, the formation of polygynous harems is not uncommon in the natural habitat. The species are secretive cave spawners (speleophils) although detailed information on their reproductive biology in the wild is limited. In the wild, the species is known to breed in holes excavated beneath aquatic and semi-aquatic plants. In captivity, artificial caves are readily accepted as breeding sites, however, these too are excavated prior to egg-laying. The eggs are adhesive and are frequently laid in rows of ca. 10 on the upper surface of the cave and produce a clutch that ranges in size from 40 to 100. Both the male and female provide active brood care, typically lasting 21–28 days, which includes guarding, herding, and feeding. It is noteworthy, however, that the female is predominantly responsible for fry care, while the male is primarily involved in territorial defence. As in all Pelvicachromis species, the gender ratio of female to male fry increases with pH. This ratio is also is known to vary at different locales in the wild. Breeding pairs of P. pulcher have been known to adopt similarly aged fry from conspecifics in aquarium trials, and it has been suggested this may be an adaption to reduce predation on their own fry. Male colour polymorphism may be indicative of behavioural differences. For example, red males obtained from a single site were found to be more aggressive and more polygamous than yellow males obtained from the same site. In addition, the species has been demonstrated to engage in cooperative territorial defence where multiple males defend a single territory.
in 1901, though subsequently a number of junior synonyms (Pelmatochromis aureocephalus, Pelmatochromis camerunensis) and misidentifications (Pelmatochromis kribensis, Pelmatochromis subocellatus var. kribensis and Pelmatochromis pulcher var. kribensis) were brought into use. Some of these synonyms are still in use by aquarium hobbyists which complicates identification of this species. Many of the common and trade names used for this species, such as kribensis
, krib, rainbow krib are derived from the erroneous binomial, Pelmatochromis kribensis.
. The species should be housed in minimum volumes of 80–90 l (169.1–190.2 ). Fine gravel should be used as a substrate
, as the species likes to burrow and to excavate caves. Quartz
itic substrates should be avoided as they interfere with larval development and may cause fry mortality. The aquarium should mimic the natural environment, and should be decorated with numerous caves, plants and hiding places. Dither fish
are useful in reducing the innate shyness of the species. The species is an unfussy feeder and will accept a range of prepared foods. They spawn readily in captivity and will accept artificial caves as substitutes for the holes used for spawning in the wild. Although tolerant of a range of water chemistries, the species has a preference for, and is more likely to breed when, maintained in soft, acidic water.
, the trait is not recessively inherited
in P. pulcher. The trait is incompletely dominant. Like many albino animals red and yellow pigments are retained, however, albino P. pulcher also show patches of melanin
in the dorsal and caudal fin around the ocelli. Langhammer (1982) reports that matings from these albino forms with red and yellow pigments produce 25% wild coloured offspring and 75% albino fry. The albino fry were themselves divided into completely amelanistic forms, and forms which retained colouration of their parents.
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
fish of the cichlid
Cichlid
Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...
family, endemic to Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...
and Cameroon
Cameroon
Cameroon, officially the Republic of Cameroon , is a country in west Central Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south. Cameroon's coastline lies on the...
. The species is popular amongst aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
hobbyists, and is most commonly sold under the name kribensis
Kribensis
Pelvicachromis pulcher is a freshwater fish of the cichlid family, endemic to Nigeria and Cameroon. The species is popular amongst aquarium hobbyists, and is most commonly sold under the name kribensis, although the species has other common names, including various derivatives of kribensis: krib,...
, although the species has other common names, including various derivatives of kribensis: krib, common krib and rainbow krib, along with rainbow cichlid and purple cichlid. Originally P. kribensis, its scientific name was changed to P. pulcher. is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "beautiful". The species is a popular cichlid for the aquarium.
Appearance, size and colouration
In the wild, male P. pulcher grow to a maximum length of approximately 12.5 centimetres (4.9 in) and a maximum weight of 9.5 gram (0.335102639998564 oz). Females are smaller and deeper bodied, growing to a maximum length of 8.1 cm (3.2 in) and a maximum weight of 9.4 g (0.331575243788052 oz). Both sexes have a dark longitudinal stripe that runs from the caudal fin to the mouth and pink to red abdomenAbdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
s, the intensity of which changes during courtship
Courtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
and breeding. The dorsal and caudal fins also may bear gold-ringed eye spots or ocelli. Males show colour polymorphisms
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
in some population
Population
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
s collected at single localities. Juveniles are monomorphic
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
until approximately six months of age.
Distribution, habitat and predators
Pelvicachromis pulcher is native to southern Nigeria and to coastal areas of Cameroon, where it occurs in warm (24 –), acidic to neutral (pHPH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
5.6–6.2), soft water
Hard water
Hard water is water that has high mineral content . Hard water has high concentrations of Ca2+ and Mg2+ ions. Hard water is generally not harmful to one's health but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling...
(12–22 mg L-1 CaCO3
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
). Populations of P. pulcher also occur outside its natural range in Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, USA
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
as a by-product of the ornamental fish trade.
The species inhabits both slow and fast-moving water, though it is only found where patches of dense vegetation are available. Other fish that share the habitat of P. pulcher include other Pelvicachromis species (Pelvicachromis taeniatus
Pelvicachromis taeniatus
Pelvicachromis taeniatus is a dwarf cichlid from West Africa that is occasionally kept as an aquarium fish. It hails from the soft-water rivers of West Africa as opposed to the East African rift lake cichlids such as the Mbuna. It is known to exist in a variety of geographically restricted...
), other cichlid species (Chromidotilapia guntheri
Chromidotilapia
Chromidotilapia is a genus of cichlid fishes. The genus contains 11 species. Of these, 9 are from Central Africa, one is from Liberia to Cameroon, while the final Chromidotilapia is a genus of cichlid fishes. The genus contains 11 species. Of these, 9 are from Central Africa, one (C. guentheri) is...
, Hemichromis cristatus and H. fasciatus, Tilapia mariae and T. zilli
Tilapia (genus)
Tilapia is a large genus of cichlid fishes endemic to Africa, except for a single species that also occurs in the Middle East. The vast majority of the species are from tropical Western and Middle Africa, but there are also a few species in Northern, Eastern and Southern Africa...
) along with Brycinus longipinnis
Alestiidae
African tetras are a group of Characiformes fish exclusively found in Africa. This family contains about 18 genera and 110 species....
and Aphyosemion
Aplocheilidae
Aplocheilidae are a family of bony fishes containing about 15 species. Formerly, the name "Aplocheilidae" was used for the Aplocheiloidei as a whole, i.e. including the Nothobranchiidae of Africa and the mainly South American Rivulidae as subfamilies. This obsolete system is sometimes still seen,...
species. The species is prey for a number of rheophilic
Rheophile
A rheophile is an organism that prefers to live in fast moving water.-Insects:*Many aquatic insects living in riffles require current to survive.*Epeorus sylvicola, a rheophilic mayfly species .-Fish:...
predators including Hepsetus odoe
Hepsetus odoe
The Hepsetus odoe, also known as the African pike or Kafue pike, is a predatory fish, and the only living member of the Family Hepsetidae.-Anatomy and Morphology:...
, Hydrocynus forskahlii
Tigerfish
Tigerfish is the common name for a variety of species from several different families of fish, usually on account of their colouration or otherwise fearsome appearance and teeth.- Alestiidae :...
, and Lates niloticus (Nile perch
Nile perch
The Nile perch is a species of freshwaterfish in family Latidae of order Perciformes. It is widespread throughout muchof the Afrotropic ecozone, being native to the Congo, Nile, Senegal, Niger, and Lake Chad, Volta, Lake Turkana and other river basins. It also occurs in the brackish waters of...
). In the natural habitat, P. pulcher have been observed excavating, defending, and sheltering in caves dug underneath plants, and these holes are also used for breeding. Not all P. pulcher, however, claim territories and many live in large, non-reproductive aggregates.
Diet
Despite the suggestion in some aquarium literature that the species feeds on wormWorm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
s, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, analysis of the stomach contents of wild P. pulcher suggests this is incorrect. A study by Nwadiaro (1985) of 161 individuals showed that the main food items were diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
s, green algae
Green algae
The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
, pieces of higher plants
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
, along with blue-green algae. Invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, though consumed, were found to be relatively uncommon food items for wild fish.
Sexual dimorphism and reproduction
Taxonomy
Pelvicachromis pulcher was originally described by George BoulengerGeorge Albert Boulenger
George Albert Boulenger FRS was a Belgian-British zoologist who identified over 2000 new animal species, chiefly fish, reptiles and amphibians.-Life:...
in 1901, though subsequently a number of junior synonyms (Pelmatochromis aureocephalus, Pelmatochromis camerunensis) and misidentifications (Pelmatochromis kribensis, Pelmatochromis subocellatus var. kribensis and Pelmatochromis pulcher var. kribensis) were brought into use. Some of these synonyms are still in use by aquarium hobbyists which complicates identification of this species. Many of the common and trade names used for this species, such as kribensis
Kribensis
Pelvicachromis pulcher is a freshwater fish of the cichlid family, endemic to Nigeria and Cameroon. The species is popular amongst aquarium hobbyists, and is most commonly sold under the name kribensis, although the species has other common names, including various derivatives of kribensis: krib,...
, krib, rainbow krib are derived from the erroneous binomial, Pelmatochromis kribensis.
In the aquarium
Pelvicachromis pulcher is a popular cichlid for the aquariumAquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
. The species should be housed in minimum volumes of 80–90 l (169.1–190.2 ). Fine gravel should be used as a substrate
Substrate (aquarium)
The substrate of an aquarium refers to the material used on the tank bottom. It can affect water chemistry, filtration, and the well-being of the aquarium's inhabitants, and is also an important part of the aquarium's aesthetic appeal...
, as the species likes to burrow and to excavate caves. Quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
itic substrates should be avoided as they interfere with larval development and may cause fry mortality. The aquarium should mimic the natural environment, and should be decorated with numerous caves, plants and hiding places. Dither fish
Dither fish
The term dither fish refers to an arbitrary group of aquarium fish used by cichlid keeping aquarists to reduce innate timidity in some species of cichlids . Dither fish swim around the top of a tank and this behavior lets shier fish know that there are no predators around and allows them to relax...
are useful in reducing the innate shyness of the species. The species is an unfussy feeder and will accept a range of prepared foods. They spawn readily in captivity and will accept artificial caves as substitutes for the holes used for spawning in the wild. Although tolerant of a range of water chemistries, the species has a preference for, and is more likely to breed when, maintained in soft, acidic water.
Selective breeding
An albino form of the species has been developed for the aquarium trade. Unlike normal albinismAlbinism
Albinism is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of an enzyme involved in the production of melanin...
, the trait is not recessively inherited
Recessive
In genetics, the term "recessive gene" refers to an allele that causes a phenotype that is only seen in a homozygous genotype and never in a heterozygous genotype. Every person has two copies of every gene on autosomal chromosomes, one from mother and one from father...
in P. pulcher. The trait is incompletely dominant. Like many albino animals red and yellow pigments are retained, however, albino P. pulcher also show patches of melanin
Melanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
in the dorsal and caudal fin around the ocelli. Langhammer (1982) reports that matings from these albino forms with red and yellow pigments produce 25% wild coloured offspring and 75% albino fry. The albino fry were themselves divided into completely amelanistic forms, and forms which retained colouration of their parents.