Julidochromis

Julidochromis
	Julidochromis regani
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cichliformes
Family:	Cichlidae
Tribe:	Lamprologini
Genus:	Julidochromis ; Boulenger, 1898
Type species
	Julidochromis ornatus; Boulenger, 1898

Last updated March 29, 2024

Julidochromis is a genus of cichlids in the subfamily Pseudocrenilabrinae. They are commonly called julies and are endemic to Lake Tanganyika in eastern Africa.^[1]^[2] This genus includes six formally described species, some with a number local variants of uncertain taxonomic status.^[2] 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.^[3]

Species

There are currently 6 formally described species in this genus:

Julidochromis dickfeldi Staeck, 1975
Julidochromis marksmithi W. E. Burgess, 2014^[4]
Julidochromis marlieri Poll, 1956
Julidochromis ornatus Boulenger, 1898 (Golden julie)
Julidochromis regani Poll, 1942 (Convict julie)
Julidochromis transcriptus Matthes, 1959 (Masked julie)

Systematics

The relationships and systematics of Julidochromis are hard to resolve with certainty. Chalinochromis is essentially similar to these fishes except for some adaptations 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.^[3]

Julidochromis species are poorly studied and a number of as yet unnamed species may exist.^[3]

Ecology and reproduction

Julidochromis species are secretive biparental substrate spawners, retreating to caves or rock crevices. Pairs are largely monogamous,^[5]^[6]^[7] however the largest male may maintain harems (polygyny)^[7] and the largest females may mate with multiple males at multiple nesting sites (polyandry).^[7]^[8] 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.^[9]

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.^[1]

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.^[7]

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 .^[1]

Julidochromis in the aquarium

Julidochromis are small-growing dwarf cichlids 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 litres (13–18 imp gal; 16–21 US gal). 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 ^[3] 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.

Related Research Articles

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.

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.

The terms shell dwellers or shelldwellers, shell-breeding, or ostracophil are descriptive terms for cichlid fish that use the empty shells of aquatic snails as sites for breeding and shelter. The terms have no taxonomic basis, although most shell-dwelling cichlids are from Lake Tanganyikas lamprologine lineage. Many shell dwelling cichlids are popular with fishkeepings and are frequently kept in aquaria.

Tropheus moorii is a species of cichlid endemic to Lake Tanganyika in Africa. Over 40 different color morphs of this species are dispersed throughout the lake, ranging from dark green to flame red and yellow. They mostly feed on filamentous algae on the rocky shallows they inhabit. T. moorii is a maternal mouthbrooder, so eggs are fertilized and young are carried in the mouth of the female while they hatch and develop.

Chalinochromis is a small cichlid genus from the subfamily Pseudocrenilabrinae. These ray-finned fishes are endemic to Lake Tanganyika in the East African Rift. The scientific name refers to the bridle-like markings across the heads of members of this genus. They have specialized jaws enabling them to feed on sponges.

Variabilichromis moorii has no common name and is a species of freshwater cichlid endemic to Lake Tanganyika in eastern Africa. It is a small ovate bodied fish named for an early collector of fish from the lake, John Edmund Sharrock Moore (1870-1947) who was a cytologist, zoologist and led an expedition to Lake Tanganyika and who discovered this species. Juveniles are usually yellow, and adults are dark brown to black in color. It reaches a total length (TL) of 10.3 centimetres (4.1 in). Currently it is the only member of its genus. V. moorii feeds on algae, zooplankton, and benthic invertebrates. It is also found in the aquarium trade.

Altolamprologus is a small genus of pseudocrenilabrine cichlids endemic to Lake Tanganyika in eastern Africa. They inhabit areas of the lake with large amounts of rock, most frequently in water two to ten metres in depth. Two formally described species comprise this genus, with perhaps one dwarf A. compressiceps-like species being considered an undescribed species by some.

Neolamprologus is a genus of cichlids endemic to eastern Africa with all but one species, Neolamprologus devosi from the Malagarasi River, occurring in Lake Tanganyika. It is the largest genus of cichlids in Lake Tanganyika and also the largest genus in the tribe Lamprologini, which includes Altolamprologus, Chalinochromis, Julidochromis, Lamprologus, Lepidiolamprologus, Telmatochromis and Variabilichromis. The latter is a monotypic genus doubtfully distinct from Neolamprologus.

Lamprologus ocellatus is a species of shell dwelling cichlid endemic to Lake Tanganyika. It is a popular aquarium fish due to its small size, appearance, and intelligence.

Telmatochromis is a small cichlid genus of the subfamily Pseudocrenilabrinae. These ray-finned fishes are endemic to the Lake Tanganyika basin in Africa.

Copadichromis geertsi is a species of haplochromine cichlid which is endemic to Lake Malawi.

Julidochromis dickfeldi is a species of cichlid endemic to Lake Tanganyika in Africa where it is only known from the southwestern portion. This species inhabits areas with rock/rubble substrates, each fish maintaining a territory around a crevice or crack. This species reaches a length of 11 centimetres (4.3 in) TL.

<i>Julidochromis marlieri</i> Species of fish

Julidochromis marlieri is a species of cichlid endemic to Lake Tanganyika where it is only known from the northwestern portion preferring rocky shorelines in deep waters. In the aquarium trade, it is commonly known as Marlier's Julie, Spotted Julie or Chequered Julie. This species reaches a length of 15 centimetres (5.9 in) TL. Adult females are larger than adult males.

The golden julie is a species of cichlid endemic to Lake Tanganyika, being found only in the extreme northern and southern shorelines of the lake in rocky environs. This species reaches a length of 8.5 centimetres (3.3 in) TL.

The convict julie 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.

The masked julie is a species of cichlid endemic to Lake Tanganyika in Africa where it is found only along the northwestern shore preferring areas with rocky substrates. They eat zooplankton and benthic invertebrates found in the algae growth in the wild. This species reaches a length of 7 centimetres (2.8 in) TL.

Lepidiolamprologus meeli is a cichlid species in the subfamily Pseudocrenilabrinae. It is endemic to Lake Tanganyika, where it is found in the waters of Burundi, the Democratic Republic of the Congo, Tanzania, and Zambia.

Neolamprologus pulcher is a species of cichlid endemic to Lake Tanganyika where it prefers locations with plenty of sedimentation. The common names for N. pulcher include daffodil cichlid, fairy cichlid, princess of Zambia and lyretail cichlid. This species can reach a length of 10 centimetres (3.9 in) TL. It can also be found in the aquarium trade.

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 is from the Malagarasi River in Tanzania, and several species of Lamprologus are from the Congo River Basin.

Telmatochromis brichardi is a species of cichlid from the tribe Lamprologini, part of the subfamily Pseudocrenilabrinae, endemic to Lake Tanganyika. It feeds on algae in rocky habitat. It is a cavity nester which forms temporary pairs for breeding, in which the male defends the territory and the female tends the brood. The specific name honours the aquarium fish dealer Pierre Brichard (1921-1990).

References

1 2 3 Pierre Brichard (1989). Cichlids and All the Other Fishes of Lake Tanganyika. New Jersey: T.F.H. Publications. ISBN 978-0-86622-667-7.
1 2 Ad Konings (1998). Tanganyikan Cichlids in their Natural Habitat. Cichlid Press. ISBN 978-0-9668255-0-3.
1 2 3 4 Julia J. Day, Simona Santini & Jaime Garcia-Moreno (2007). "Phylogenetic relationships of the Lake Tanganyika cichlid tribe Lamprologini: The story from mitochondrial DNA". Molecular Phylogenetics and Evolution . 45 (2): 629–642. doi:10.1016/j.ympev.2007.02.025. PMID 17416538.
↑ Burgess, W.E. (2014): Julidochromis marksmithi, A New Species of Julidochromis from the Tanzanian Coast of Lake Tanganyika. Tanganika Magazyn, 15: 40-49.
↑ Satoshi Yamagishi & Masanori Kohda (1996). "Is the cichlid fish Julidochromis marlieri polyandrous?". Ichthyological Research . 43 (4): 469–471. Bibcode:1996IchtR..43..469Y. doi:10.1007/BF02347645. S2CID 45783664.
↑ Tetsuo Kuwamura (1997). "The evolution of parental care and mating systems among Tanganyikan cichlids". In Hiroya Kawanabe, Michio Hori & Makoto Nagoshi (ed.). Fish Communities in Lake Tanganyika. Kyoto: Kyoto University Press. pp. 57–86. ISBN 978-4-87698-042-0.
1 2 3 4 Satoshi Awata & Masanori Kohda (2004). "Parental roles and the amount of care in a bi-parental substrate brooding cichlid: the effect of size differences within pairs" (PDF). Behaviour . 141 (9): 1135–1149. CiteSeerX 10.1.1.579.7554 . doi:10.1163/1568539042664623.
↑ Tomoki Sunobe (2000). "Social structure, nest guarding and interspecific relationships of the cichlid fish (Julidochromis marlieri) in Lake Tanganyika" (PDF). African Study Monographs . 21: 83–89. Archived from the original (PDF) on 2010-12-06. Retrieved 2008-08-30.
↑ George W. Barlow & Jonathan S. Lee (2005). "Sex-reversed dominance and aggression in the cichlid fish Julidochromis marlieri" (PDF). Annales Zoologici Fennici . 42: 477–483.