Julidochromis
Encyclopedia
Julidochromis is a genus
of cichlid
s in the subfamily Pseudocrenilabrinae
. They are commonly called julies and are endemic to Lake Tanganyika
in eastern Africa. This genus includes at least 5 species
, each with a number of subspecies
and local variants of uncertain taxonomic status. Further taxonomic work is required to determine how many species exist; the closely related Chalinochromis
with two more species is sometimes included here and this may be correct. Hybridization makes attempts to determine relationships with molecular phylogenetic methods difficult.
These ray-finned fish are smallish to mid-sized (about 7 centimetre) and have a yellowish background colour with black lengthwise stripes or a checkerboard
pattern.
The relationships and systematics
of Julidochromis are hard to resolve with certainty. Chalinochromis
is essentially similar to these fishes except for some adaptation
s for feeding on sponges. In their mtDNA NADH dehydrogenase
subunit
2 sequence
, Chalinochromis are closer to J. dickfeldi
, the Golden Julie
(J. ornatus) and the Masked Julie
(J. transcriptus) – in particular the latter two – than to any other living fish, while J. marlieri
and the Convict Julie
(J. regani) are closer to Telmatochromis
. Julidochromis thus might need to be split in two, with Chalinochromis included in one lineage. Alternatively, there has twice been successful intergeneric hybridization between particular lineages of Julidochromis males and Chalinochromis females (males generally do not pass on mtDNA to their offspring), the julies being closer to Telmatochromis in this case. Yet another possibility is that Julidochromis is monophyletic and includes Chalinochromis; in this scenario males of the common ancestor of J. marlieri and J. regani would have hybridized with females of the common ancestor of Telmatochromis.
Julidochromis species
are poorly studied and a number of as yet unnamed species may exist. In the order of relatedness, the described species are:
) and the largest females may mate with multiple males at multiple nesting sites (polyandry
). This has been recorded in both the wild and the aquarium.
If a pair-bond is broken, the larger fish will drive the smaller fish out of the territory, sometimes killing him in the process. In some species in this genus, such as Julidochromis marlieri
, females are substantially larger than the males, and a female Julidochromis will often dominate a male larger than herself.
Julidochromis species have two spawning rhythms. Sometimes they deposit a large number of eggs (up to several hundred) every four to six weeks. Other times they spawn sequentially, laying a small number of eggs every few days. Sequential spawning results in there being fry of different ages living together in the same nest.
They prefer to lay their eggs in caves or other crevices. After spawning, both parents tend the eggs by mouthing them to rid of algae and fanning them to increase oxygen flow. The majority of parental care is done by the smaller fish in a pair, but this has been found to be influenced by the degree of size difference within a pair.
A pair of breeding fish must guard their nest from other cichlids trying to eat their offspring. Common intruders in the lake include Tropheus
, Simochromis
, and Petrochromis
.
Julidochromis are small-growing dwarf cichlid
s and easy to spawn and care for if their basic needs are fulfilled. Like all Lake Tanganyika
cichlids, they are best maintained in hard alkaline water, with a pH of 8.5–9.0 and a hardness of 12–14 kH, and in aquaria no smaller than 60–80 l (126.8–169.1 ). Only one species of Julidochromis should be kept in any single aquarium, as the species within this genus tend to hybridise easily. As noted above, hybridisation with Chalinochromis
and/or Telmatochromis
is suspected, and it is common enough in Lamprologini
to better avoid keeping more than one species of this tribe
per aquarium.
The tank should be decorated with rocks to form caves and passageways as shelter; like many other Rift Valley cichlids they tend to be territorial and somewhat aggressive. However, Julidochromis can be shy in the aquarium and the use of dither fish
may reduce their tendency to remain hidden. Despite this, like many Rift Lake cichlids they can be aggressive. It is therefore best to keep them not with general tropical fish, but with other cichlids.
As noted above, Julidochromis species are monogamous, but pair bonds can break and hostilities may result in the death of one of the pair, generally the smaller fish. If a pair does split in an aquarium it is often best to separate the pair. Fry can be maintained with the parents and should be fed protein
-rich foods such as baby brine shrimp
. Parents can sometimes be found leading their fry around the aquarium.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of 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...
s in the subfamily Pseudocrenilabrinae
Pseudocrenilabrinae
The Pseudocrenilabrinae is a subfamily in the cichlid family of fishes to which, according to a study from 2004, includes all the Middle Eastern and African cichlids with the exception of the unusual Heterochromis multidens and the Malagasy species. Previous authors recognized additional African...
. They are commonly called julies and are endemic to Lake Tanganyika
Lake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
in eastern Africa. This genus includes at least 5 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, each with a number of subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
and local variants of uncertain taxonomic status. Further taxonomic work is required to determine how many species exist; the closely related Chalinochromis
Chalinochromis
Chalinochromis is a small and disputed cichlid genus from the subfamily Pseudocrenilabrinae; it contains just two species. These ray-finned fishes are endemic to Lake Tanganyika in Eastern Africa's Great Rift Valley. The scientific name refers to the bridle-like markings across the heads of members...
with two more species is sometimes included here and this may be correct. Hybridization makes attempts to determine relationships with molecular phylogenetic methods difficult.
These ray-finned fish are smallish to mid-sized (about 7 centimetre) and have a yellowish background colour with black lengthwise stripes or a checkerboard
Checkerboard
A checkerboard or chequerboard is a board of chequered pattern on which English draughts is played. It is an 8×8 board and the 64 squares are of alternating dark and light color, often red and black....
pattern.
Systematics
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...
of Julidochromis are hard to resolve with certainty. Chalinochromis
Chalinochromis
Chalinochromis is a small and disputed cichlid genus from the subfamily Pseudocrenilabrinae; it contains just two species. These ray-finned fishes are endemic to Lake Tanganyika in Eastern Africa's Great Rift Valley. The scientific name refers to the bridle-like markings across the heads of members...
is essentially similar to these fishes except for some adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
s for feeding on sponges. In their mtDNA NADH dehydrogenase
NADH dehydrogenase
NADH dehydrogenase is an enzyme located in the inner mitochondrial membrane that catalyzes the transfer of electrons from NADH to coenzyme Q...
subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
2 sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
, Chalinochromis are closer to J. dickfeldi
Julidochromis dickfeldi
Julidochromis dickfeldi is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika in Africa where it is found in the Democratic Republic of the Congo, Tanzania, and Zambia.-References:...
, the Golden Julie
Golden julie
The golden julie is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika, being found only in the extreme northern and southern shorelines of the lake in rocky environs.-References:...
(J. ornatus) and the Masked Julie
Masked julie
The masked julie is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika in Africa where it is found in Burundi and the Democratic Republic of the Congo.Julidochromis transcriptus is a dwarf Julidochromis species. The Masked Julie was described by Matthes in 1959...
(J. transcriptus) – in particular the latter two – than to any other living fish, while J. marlieri
Julidochromis marlieri
Julidochromis marlieri is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika in Africa where it is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. In the aquarium trade, it is commonly known as Marlier's Julie or Spotted Julie.-References:*...
and the Convict Julie
Convict julie
The Convict Julie, Julidochromis regani, is a cichlid species in the subfamily Pseudocrenilabrinae family endemic to Lake Tanganyika. Hence it is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. The fish is named after Charles Tate Regan.This species is closely related...
(J. regani) are closer to Telmatochromis
Telmatochromis
Telmatochromis is a small cichlid genus of the subfamily Pseudocrenilabrinae. These ray-finned fishes are endemic to Lake Tanganyika in East Africa.-Systematics:7 species are included here...
. Julidochromis thus might need to be split in two, with Chalinochromis included in one lineage. Alternatively, there has twice been successful intergeneric hybridization between particular lineages of Julidochromis males and Chalinochromis females (males generally do not pass on mtDNA to their offspring), the julies being closer to Telmatochromis in this case. Yet another possibility is that Julidochromis is monophyletic and includes Chalinochromis; in this scenario males of the common ancestor of J. marlieri and J. regani would have hybridized with females of the common ancestor of Telmatochromis.
Julidochromis species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are poorly studied and a number of as yet unnamed species may exist. In the order of relatedness, the described species are:
- Julidochromis dickfeldiJulidochromis dickfeldiJulidochromis dickfeldi is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika in Africa where it is found in the Democratic Republic of the Congo, Tanzania, and Zambia.-References:...
- (ChalinochromisChalinochromisChalinochromis is a small and disputed cichlid genus from the subfamily Pseudocrenilabrinae; it contains just two species. These ray-finned fishes are endemic to Lake Tanganyika in Eastern Africa's Great Rift Valley. The scientific name refers to the bridle-like markings across the heads of members...
might belong in this position) - Julidochromis ornatus – Golden JulieGolden julieThe golden julie is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika, being found only in the extreme northern and southern shorelines of the lake in rocky environs.-References:...
- Julidochromis transcriptus – Masked JulieMasked julieThe masked julie is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika in Africa where it is found in Burundi and the Democratic Republic of the Congo.Julidochromis transcriptus is a dwarf Julidochromis species. The Masked Julie was described by Matthes in 1959...
- Julidochromis marlieriJulidochromis marlieriJulidochromis marlieri is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika in Africa where it is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. In the aquarium trade, it is commonly known as Marlier's Julie or Spotted Julie.-References:*...
- Julidochromis regani – Convict JulieConvict julieThe Convict Julie, Julidochromis regani, is a cichlid species in the subfamily Pseudocrenilabrinae family endemic to Lake Tanganyika. Hence it is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. The fish is named after Charles Tate Regan.This species is closely related...
Ecology and reproduction
Julidochromis species are secretive biparental substrate spawners, retreating to caves or rock crevices. Pairs are largely monogamous, however the largest male may maintain harems (polygynyPolygyny
Polygyny is a form of marriage in which a man has two or more wives at the same time. In countries where the practice is illegal, the man is referred to as a bigamist or a polygamist...
) and the largest females may mate with multiple males at multiple nesting sites (polyandry
Polyandry
Polyandry refers to a form of marriage in which a woman has two or more husbands at the same time. The form of polyandry in which a woman is married to two or more brothers is known as "fraternal polyandry", and it is believed by many anthropologists to be the most frequently encountered...
). This has been recorded in both the wild and the aquarium.
If a pair-bond is broken, the larger fish will drive the smaller fish out of the territory, sometimes killing him in the process. In some species in this genus, such as Julidochromis marlieri
Julidochromis marlieri
Julidochromis marlieri is a species of fish in the Cichlidae family. It is endemic to Lake Tanganyika in Africa where it is found in Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia. In the aquarium trade, it is commonly known as Marlier's Julie or Spotted Julie.-References:*...
, females are substantially larger than the males, and a female Julidochromis will often dominate a male larger than herself.
Julidochromis species have two spawning rhythms. Sometimes they deposit a large number of eggs (up to several hundred) every four to six weeks. Other times they spawn sequentially, laying a small number of eggs every few days. Sequential spawning results in there being fry of different ages living together in the same nest.
They prefer to lay their eggs in caves or other crevices. After spawning, both parents tend the eggs by mouthing them to rid of algae and fanning them to increase oxygen flow. The majority of parental care is done by the smaller fish in a pair, but this has been found to be influenced by the degree of size difference within a pair.
A pair of breeding fish must guard their nest from other cichlids trying to eat their offspring. Common intruders in the lake include Tropheus
Tropheus
Tropheus is a small genus of six species of cichlid fish endemic to Lake Tanganyika in East Africa. The genus Tropheus is widespread across all regions of lake Tanganyika, from Burundi in the North to Zambia in the South.Males and females are relatively similar but do display obvious sexual...
, Simochromis
Simochromis
Simochromis is a genus of fish in the Cichlidae family.It contains the following species:* Simochromis babaulti* Simochromis diagramma* Simochromis margaretae* Simochromis marginatus* Simochromis pleurospilus...
, and Petrochromis
Petrochromis
Petrochromis is a small genus of seven formally described cichlid species, and at least 7 undescribed species, all endemic to Lake Tanganyika in east Africa.-Species:* Petrochromis famula Matthes & Trewavas, 1960...
.
Julidochromis in the aquarium
Dwarf cichlid
Dwarf cichlid is a term used by fishkeeping hobbyists to describe an arbitrary assemblage of small-sized fish from the family Cichlidae. Although the grouping is widely used in the aquarium industry and hobby, the grouping has no taxonomic or ecological basis and is poorly defined...
s and easy to spawn and care for if their basic needs are fulfilled. Like all Lake Tanganyika
Lake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
cichlids, they are best maintained in hard alkaline water, with a pH of 8.5–9.0 and a hardness of 12–14 kH, and in aquaria no smaller than 60–80 l (126.8–169.1 ). Only one species of Julidochromis should be kept in any single aquarium, as the species within this genus tend to hybridise easily. As noted above, hybridisation with Chalinochromis
Chalinochromis
Chalinochromis is a small and disputed cichlid genus from the subfamily Pseudocrenilabrinae; it contains just two species. These ray-finned fishes are endemic to Lake Tanganyika in Eastern Africa's Great Rift Valley. The scientific name refers to the bridle-like markings across the heads of members...
and/or Telmatochromis
Telmatochromis
Telmatochromis is a small cichlid genus of the subfamily Pseudocrenilabrinae. These ray-finned fishes are endemic to Lake Tanganyika in East Africa.-Systematics:7 species are included here...
is suspected, and it is common enough in Lamprologini
Lamprologini
Lamprologini is a tribe of African cichlid fishes. It contains seven genera and nearly 100 species. Over half of the species in this tribe are in the large genus Neolamprologus. Most genera in the tribe are endemic to Lake Tanganyika, but one species of Neolamprologus Lamprologini is a tribe of...
to better avoid keeping more than one species of this tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
per aquarium.
The tank should be decorated with rocks to form caves and passageways as shelter; like many other Rift Valley cichlids they tend to be territorial and somewhat aggressive. However, Julidochromis can be shy in the aquarium and the use of 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...
may reduce their tendency to remain hidden. Despite this, like many Rift Lake cichlids they can be aggressive. It is therefore best to keep them not with general tropical fish, but with other cichlids.
As noted above, Julidochromis species are monogamous, but pair bonds can break and hostilities may result in the death of one of the pair, generally the smaller fish. If a pair does split in an aquarium it is often best to separate the pair. Fry can be maintained with the parents and should be fed protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
-rich foods such as baby brine shrimp
Brine shrimp
Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period...
. Parents can sometimes be found leading their fry around the aquarium.
Further reading
- Barlow, G. W. (2002): The Cichlid Fishes - Nature's grand experiment in evolution. Basic Books.
- Smith, M. P. (1998): Lake Tanganyikan Cichlids - a complete pet owners manual. Barron's Educational.