Julidochromis is a genus of cichlids 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 7–15 centimetres or 2.8–5.9 inches) 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 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.
Julidochromis species are poorly studied and a number of as yet unnamed species may exist. In the order of relatedness, the described species are:
Julidochromis species are secretive biparental substrate spawners, retreating to caves or rock crevices. Pairs are largely monogamous, however the largest male may maintain harems (polygyny) 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 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 to better avoid keeping more than one species of this tribe per aquarium.
These ray-finned fish are smallish to mid-sized (about 7–15 centimetres or 2.8–5.9 inches) 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 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.
Julidochromis species are poorly studied and a number of as yet unnamed species may exist. In the order of relatedness, the described species are:
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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.
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