Hemichromis is a genus of fishes from the cichlid family, known in the aquarium trade as jewel cichlids. Jewel cichlids are native to Africa. Within West Africa, Hemichromis species are found in creeks, streams, rivers and lakes with a variety of water qualities including brackish water lagoons.[1][2] As traditionally defined, the genus includes two distinctly different groups: The five-spotted cichlid group (Hemichromissensu stricto) and the true jewel cichlid group (Rubricatochromis), which sometimes are recognized as distinct genera.[3]
Maximum size reported for the different species of Hemichromis ranges from 6.5 to 26.5 cm (2.5–10.5 in) in total length.[1][4] Maximum sizes in aquaria tend to be slightly smaller than in the wild.[1]
Many Hemichromis species are brightly coloured, though brighter body colouration is generally evident during breeding. Sexual dimorphism is limited, though male jewel cichlids are typically more brightly coloured and in some species have more pointed anal, ventral and dorsal fins. In some species, such as Hemichromis cristatus, the females can have coloring as bright as the males. Like most cichlids, jewel cichlids have highly developed brood care. Hemichromis species typically form monogamous breeding pairs and the female spawns on a flat surface such as a leaf or stone. Both parents guard the eggs, and participate in fry raising.
Taxonomy
[edit]H. fasciatus, the largest species in the genus[4]A female H. lifalili fanning her eggs
This genus consists of two distinct groups that possibly should be moved into separate genera. The first group, the so-called five-spotted cichlids (including H. elongatus, H. faciatus and H. frempongi), would remain in the genus Hemichromis, while the rest, the true jewel cichlids, would be moved to their own genus.[5] In 2022, the new genus Rubricatochromis was described for the true jewel cichlids.[3]
The species level taxonomyofHemichromis is not fully resolved.[5][6] Although some of the localized species are well-defined, this is not the case for all the more widespread species and there are several distinct color forms of unclear taxonomic status.[6] For example, H. faciatus of the Nile basin and those in West Africa may belong to separate species,[7] but H. frempongiofLake Bosumtwi might be a synonymofH. fasciatus.[8]H. elongatus of the Congo River basin and upper Zambezi may represent a species that is distinct from H. faciatus elsewhere, and "dwarf" populations in lakes Barombi Koto and Mboandong may also be distinct.[6] In the Nile delta, there appear to be two morphologically distinct populations that traditionally have been included in, but might be separate from, H. letourneuxi elsewhere in the Nile system.[7] A comprehensive study of the genus also points to the existence of two undescribed species of jewel cichlids in the Guinea region.[5]H. saharae was generally considered a synonym of H. letourneuxi until 2014 where a genetic study confirmed its distinction,[9] although some have opted to retain the two as a single species.[8] The taxonomic confusion in this genus has been further complicated by fish in the aquarium trade, where there have been frequent misidentification, hybridization between species and selective breeding. For example, the introduced population in Florida, which is based on aquarium fish, was identified as H. bimaculatus up until the 1990s, but likely are H. letourneuxi or hybrids.[10] A similar pattern can be seen in introduced populations elsewhere that traditionally were identified as H. bimaculatus, but likely are other species, especially H. letourneuxi.[11]
Jewel cichlids are neither suited to beginners, nor the usual community tank. Several young specimens may be kept in a spacious aquarium, with stones and wood for cover until a pair forms prior to breeding. Their innate aggression makes them good candidates for keeping in a monospecies aquarium, however this depends on a number of factors similar to all tropical cichlid fish; swimming and territory space, other aquatic inhabitants, diet and feeding frequency and tank layout.
Jewel cichlids are omnivorous and will eat both live foods and fish flakes.
Here are some general guidelines for setting up a tank for Jewel Cichlid[13]
Tank Size: A minimum tank size of 30 gallons is recommended for a pair of Jewel Cichlids, with an additional 10 gallons for each additional fish.
Water Parameters: Jewels prefer slightly acidic to neutral water (pH 6.5–7.5) with a temperature range of 75–82 °F. Keep the water clean by performing regular water changes (20–30% every 2 weeks).
Substrate and Decorations: Jewels like to dig, so a substrate of fine gravel or sand is recommended. They also enjoy having plenty of hiding places and territory to claim, so provide rocks, caves, and driftwood in the tank.
Filtration and Aeration: A good filtration system is important to maintain good water quality in the tank. Aeration is also recommended to increase oxygenation and water flow.
Tankmates: Jewels can be aggressive and territorial, so it's best to keep them with similarly-sized and equally-aggressive fish. Other cichlid species such as Convicts, Green Terrors, and Fire mouth can make good tankmates.
Feeding: Jewels are omnivorous and will eat a variety of foods, including pellets, flakes, frozen foods, and live foods. Offer a mix of these foods to provide a balanced diet.
^ abLamboj, A.; Koblmüller, S. (2022). "Molecular phylogeny and taxonomic revision of the cichlid genus Hemichromis (Teleostei, Cichliformes, Cichlidae), with description of a new genus and revalidation of H. angolensis". Hydrobiologia. 850 (10–11): 2177–2198. doi:10.1007/s10750-022-05060-y. S2CID253274285.
^ abcLamboj, A.; M. Petrasko; R. Schelly (2015). "Phylogeny and systematics of Hemichromis (Perciformes: Cichlidae)". Cichlid Science. 108.
^ abcStiassny, M.L.J.; A. Lamboj; D. De Weirdt; G.G. Teugels (2008). "Cichlidae". In M.L.J. Stiassny; G.G Teugels; C.D. Hopkins (eds.). The fresh and brackish water fishes of Lower Guinea, West-Central Africa / Poissons d'Eaux Douces et Saumâtres de Basee Guinée, Ouest de l'Afrique Centrale. Vol. 2. Muséum national d'Histoire naturelle, Musée Royal de l'Afrique Centrale. pp. 269–403.
^ abNeumann, D.; H. Obermaier; T. Moritz (2016). "Annotated checklist for fishes of the Main Nile Basin in the Sudan and Egypt based on recent specimen records (2006-2015)". Cybium. 40 (4): 287–317. doi:10.26028/cybium/2016-404-004.
^Bitja-Nyom, Arnold Roger, et al. "A systematic revision of the five-spotted Hemichromis complex (Cichliformes: Cichlidae) from West Africa and Lower Guinea, with the description of a new species from Cameroon." Hydrobiologia (2021): 1-25.
