Lake Tanganyika cichlids — species, locations & maps

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Tropheus duboisi 'Halembe'<br><font color=gray>Maswa duboisi</font>

Tribe / Genus:	Tropheini / Tropheus
Type locality:	Bemba, Lake Tanganyika, Democratic Republic of Congo
Biotope:	Rocky shores, including deeper and more sediment-rich zones compared to other Tropheus species. The species is most abundant between 6 and 10 m depth but has been recorded down to approximately 30 m.
Geographic distribution:	It is likely that the species once had a much wider or more continuous distribution. Today its occurrence is fragmented, with a patchy distribution pattern. The species is known from Bemba in DR Congo, from Muguruka in Burundi, and in Tanzania from the Kigoma area northwards to Gombe National Park, as well as from the stretch between Halembe and Kiti Point and from the area between Lufungu Bay and Katumbi Point.
Typical adult size:	Up to about 14 cm total length in imported fish; in aquaria it may sometimes exceed 15 cm. Females are usually slightly smaller than males.
Sexual dimorphism:	No difference in color pattern between sexes; males usually grow slightly larger than females.
Recommended aquarium size:	An aquarium with a minimum volume of 500 liters and a length of at least 150 cm is recommended.
Aquarium setup:	Use fine sand as the substrate. To provide sufficient refuges for persecuted cichlids, place a substantial number of rocks in the tank. It is advisable to use the rocks to create at least one, or several, visual barriers. There are no plants in the natural habitat of Tropheus, so they are not required in the aquarium. If plants are desired for aesthetic reasons or to slightly assist with water quality, choose species with tougher leaves (Vallisneria, Anubias, Ceratophyllum, etc.), which are generally left untouched by Tropheus. Water chemistry is of critical importance. The pH must be above 7.5 (approximately 7.5 to 9.5). Temperature should be kept consistently between 24 and 27°C and must never exceed 29°C, as this can be fatal. Higher temperatures increase oxygen demand while simultaneously reducing dissolved oxygen levels. In Lake Tanganyika, the upper 40 m of water is very clear and rich in oxygen; therefore, the aquarium should also be well oxygenated using air pumps, filter outlets directed toward the surface, or circulation pumps that enhance surface agitation. Tropheus are highly sensitive to ammonia, nitrite, and nitrate. The filtration system must therefore be powerful and biologically mature. Ammonia and nitrite cause immediate poisoning, while elevated nitrate levels lead to a gradual deterioration of health. Regular weekly water changes of 30–50% are essential, and replacement water should also be well oxygenated. It is practically impossible to recreate the natural environment of Tropheus in an aquarium, as this would require an extremely large system. In the wild, most adult Tropheus are territorial; similarly, in the aquarium one or a few territorial males occupy defined areas, leaving limited space for other males and females. Because food availability in the aquarium is higher than in nature, non-territorial individuals tend to suppress the need to establish separate feeding territories. Tropheus are best maintained in relatively large groups of approximately 15 to 25 individuals. In such groups, there may be several males, but there should be at least three to four females per male. Typically, only one male becomes dominant, occupies a territory, and is the only individual that spawns. In community aquaria, somewhat smaller groups may also be kept. Suitable tank mates include other herbivorous Tanganyikan cichlids, such as smaller Petrochromis species, goby cichlids (Eretmodus, Tanganicodus, and Spathodus)... Different geographic variants of the same Tropheus species should never be kept together due to the high risk of hybridization. Different Tropheus species may be kept together, preferably those that naturally occur at the same locations. For example, T. duboisi can generally be housed with other Tropheus species, although its lower aggressiveness often makes a species-only aquarium the better choice. When establishing a group, it is best to introduce a larger number of juveniles so territories develop gradually as the fish grow. Introducing adults often results in extremely violent territorial conflicts. Adding Tropheus to an already established group with defined territories is also very difficult.
Diet:	Herbivorous. In the lake, Tropheus feed primarily on filamentous algae from the aufwuchs. In the aquarium, some of these algae may grow on rocks, but usually not in sufficient quantity to form the main diet. As a staple, flake food with a high spirulina content is most suitable. Occasionally, foods such as Daphnia, Cyclops, and Mysis can be offered, as some of this prey is also ingested during natural algae grazing. High-protein foods must be strictly avoided, as they can be lethal. Tropheus have a very long digestive tract adapted to a low-protein diet, and excessive protein intake can quickly lead to the condition known as bloat, to which they are extremely susceptible. Adult fish should be fed once per day, only as much as they can consume within two minutes. Feeding can also be divided into several smaller meals per day, provided the total daily amount remains the same.
Breeding:	Typical mouthbrooders. Tropheus usually begin breeding at around 12 months of age, although some individuals may start considerably later. Spawning begins with the dominant male chasing the female. In the wild, breeding starts when a female enters the male’s territory and begins feeding there. In the aquarium, the male’s territory often encompasses most or all of the tank, resulting in continuous chasing of females, even when they are not yet sexually mature. A receptive female responds to the male’s courtship displays and follows him to his territory. Spawning usually occurs in the calmest part of the territory, often on a gently sloping surface. Eggs are laid one at a time, immediately taken into the female’s mouth, and fertilized by the male during this process. Eggs are relatively large (approximately 5–7 mm), resulting in small broods of about 6–16 eggs. The female carries the developing fry for around 24–26 days, after which she gradually releases them and guards them for several days. The male plays no role in brood care and often drives the female away immediately after spawning. Unlike many other mouthbrooding cichlids, female Tropheus continue to feed while carrying fry. In some species, females may accept food without swallowing it, with the food consumed only by the fry, whereas in other species females feed normally together with the fry.
Aggression:	Unlike most Haplochromis in Lake Tanganyika, female Tropheus also maintain feeding territories. Male territories are generally one to two times larger than those of females. In the aquarium, limited space usually allows only a few, or even a single, dominant male to hold a territory, from which all other cichlids are chased away. Aggression is strongest toward conspecifics, while other species are typically tolerated to a greater extent. Due to pronounced intraspecific aggression, Tropheus should be kept in larger groups to distribute aggression among more individuals.
Special notes:	Tropheus duboisi is considered the oldest extant species of the genus. Unlike other Tropheus, it regularly inhabits deeper and more sediment-rich parts of rocky habitats, being most common between 6 and 10 m but occurring down to about 30 m depth (Ad Konings 2019). Its deeper distribution is linked to competitive pressure from other, more aggressive Tropheus species and from Petrochromis, which do not tolerate T. duboisi in shared feeding areas. Adults typically show a blue-grey head and a dark to black body with a white to yellowish vertical bar on the chest, while juveniles are black with rows of white to pale blue spots. The species is distinguished by a narrower, rounded sub-terminal mouth and by having five spines in the anal fin. Five geographic variants are recognized: Bemba – the only variant occurring in DR Congo and the type locality; characterized by a narrow white to pale yellow bar that is often incomplete. Muguruka – reported as entirely black without a white bar or flank patch (Ntakimazi 1995; Van Steenberge 2014). Gombe NP, Kigoma and Cape Bangwe – populations around the Kigoma area; the bar is pure white and only rarely yellowish, often incomplete. Maswa, Cape Kabogo, Mkuyu, Segunga and Halembe – commonly known as the Maswa variant and the most widespread in aquaristics; it has the widest flank bar, usually yellow in the upper part and white in the lower part, with fully yellow bars occurring more rarely. Unfortunately, this variant has become a victim of its own popularity, and wild Maswa populations have been severely reduced due to excessive collecting in the lake. Katumba Point, Bulu Point, Karilani Island, Miyako Point and Luagala Point – characterized by a narrow white bar, often incomplete and sometimes reduced to one or two elongated spots.