Demasoni

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: sand.

Behavior

Plant interaction: plant ripper.

Feeding

Predominantly herbivorous, feeding on aufwuchs (microalgae, diatoms, and small invertebrates scraped from rock surfaces with bicuspid teeth) in the wild. In the aquarium, spirulina-based flake and pellets should form the bulk of the diet, with blanched peas, blanched spinach, blanched zucchini, and nori seaweed as supplemental greens. Frozen brine shrimp and mysis can be offered occasionally for variety but not as a staple; high-protein food fed regularly contributes to Malawi bloat, the leading cause of premature death in this species. Tubifex and bloodworm (red mosquito larvae) are particularly risky and most experienced Mbuna keepers avoid them entirely. Feed small portions two or three times daily; the fish are aggressive feeders and a single large meal triggers gorging in the dominant fish while subordinates miss out.

Compatibility

• One of the most aggressive small mbuna in the hobby. The 7 to 8 cm adult size is misleading; demasoni pack the territorial intensity of fish twice the size, particularly males defending feeding territories
• Group sizing is critical. The standard recommendation is a group of twelve or more in at least 250 litres (preferably 90 to 120 cm tank length), with overlapping sightline breaks from rock work. In smaller groups the dominant male kills rivals one by one until the colony collapses
• Tankmates should be other Lake Malawi mbuna of similar size and water requirements. Do not house with peacock cichlids, haps, hap-type fish, or non-mbuna; the temperament mismatch leads to the more peaceful species dying
• Avoid keeping with other vertically-barred blue mbuna (Pseudotropheus saulosi, Cynotilapia, Maylandia/Metriaclima species with similar patterning). Visual similarity triggers intense interspecific aggression in mbuna
• Yellow lab (Labidochromis caeruleus) is the classic safer tankmate: a different colour pattern, a milder temperament for an mbuna, and matched water parameters
• Synodontis catfish from Lake Tanganyika (S. petricola, S. multipunctatus) handle the hard alkaline water and stay in the lower zone, providing bottom activity without territorial overlap

Origin and habitat

A dwarf mbuna endemic to Lake Malawi (family Cichlidae, order Cichliformes), with an extremely restricted range. The type specimens were collected at Pombo Rocks in Tanzanian waters, about halfway up the lake, south of the Ruhuhu River delta; the species is also found at Ndumbi Reef (also written Ndumbi Point), roughly four kilometres to the north. The IUCN estimates the area of occupancy at around four square kilometres, with a mature-population estimate of 500 to 1,000 individuals, and lists the species as Vulnerable under criteria D1+2 (2018 assessment). The narrow range makes the wild population particularly susceptible to overcollection for the aquarium trade. Adrianus F. (Ad) Konings described the species in 1994 (Cichlids Yearbooks 4:24-27) as Pseudotropheus demasoni, with the original paper title 'a sexually monomorphic cichlid from the Tanzanian coast of Lake Malawi'. In 2016 the species was transferred to a newly erected genus, Chindongo, by Li, Konings, and Stauffer; the type species of the new genus is Chindongo bellicosus. The genus name Chindongo is a common name in Malawi for small, rock-dwelling fish. The species epithet honours Laif DeMason of the United States, an importer, exporter, and breeder of cichlids. The body pattern is a cobalt-blue ground colour overlaid with six or seven bold dark-blue-to-black vertical stripes; males and females share the same pattern (sexual monomorphism), and the only reliable visual differences are slight size dimorphism (males reach about 8 cm, females about 6.5 cm) and the egg spots on the male's anal fin being more pronounced. Records give a theoretical maximum of around 10 cm SL; Records list 6.3 cm SL. The fish feeds by combing algae strands off rock surfaces with specialised bicuspid teeth (aufwuchs grazing) and is rarely seen far from the rocky substrate. Despite the small size, the species is among the most aggressive mbuna in the hobby, particularly toward conspecifics. Wild habitat is shallow rocky reefs at three to four metres depth. Most trade stock is now captive-bred.

Breeding

A maternal mouthbrooder following the standard Lake Malawi mbuna pattern. The dominant male sets up a territory in the rock work, often on a flat or slightly inclined surface, and displays his intensified colour and twitching motion to passing females. A receptive female deposits a few eggs at a time, immediately turns to collect them in her mouth, and is induced to take in sperm by approaching the male's anal fin, where the conspicuous egg-spot pattern functions as a release stimulus. A complete clutch typically runs 5 to 15 eggs, which the female holds in her buccal cavity for 18 to 21 days while refusing food. Released fry are about 8 to 10 mm long and accept crushed spirulina flake and finely powdered cichlid food immediately. Female demasoni often refuse to eat for an extended period after release, so well-conditioned breeders typically remove the female to a recovery tank with food and reduced aggression. In a community mbuna tank with extensive rock cover, a small percentage of fry survive in cracks and crevices. For higher survival, strip the female at 14 to 18 days into a separate fry tank, or let her release into a breeding net. Small clutch size and slow growth make colony expansion comparatively slow for an mbuna.

Common problems

Aggression-driven deaths are the dominant management problem. In a group too small to spread aggression (under about ten in a 250-litre tank, or under twelve in a more typical 200-litre setup), the dominant male systematically eliminates rivals starting with subordinate males and progressing to subordinate females. The standard mitigation is overcrowding: keep a starting group of fifteen or more juveniles, accept the natural die-off as the hierarchy sorts itself out, and end up with a stable colony of one dominant male and four or five subordinates. Extensive rock piling with many broken sightlines is essential because line-of-sight territoriality is what drives the aggression. Malawi bloat is the second main cause of premature death. Symptoms are swollen belly, stringy white feces, lethargy, rapid breathing, and loss of appetite; by the time symptoms are clearly visible the disease has progressed and is often fatal. The condition is caused by a combination of dietary stress (too much protein, particularly tubifex and red mosquito larvae) and bacterial or protozoan opportunism. Treatment is metronidazole (Flagyl) at the earliest sign of symptoms, ideally with simultaneous improvement of diet and water quality. Because males and females are visually identical, you cannot buy a specific sex ratio at the store; the standard approach is to buy twelve or more juveniles and let them sort themselves into the typical 1:4 dominant-male-to-female ratio over time. Stunting and weight loss in subordinate fish indicate that the social hierarchy is too intense for the current tank size and stocking.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size