Polystigma care guide
Polystigma (Nimbochromis polystigma) — minimum tank 500 L, temperature 24-27 °C, pH 7.8-8.6.
Compiled by Aquairi from published sources · Published · Updated
Overview
Nimbochromis polystigma is a Lake Malawi haplochromine predator that ambushes prey by lying on its side on the substrate, mimicking a dead fish, then striking at smaller cichlids attracted to it. Adults reach about 25 cm. The body bears a marbled brown-and-white pattern.
Taxonomy
- Family: Cichlidae
- Genus: Nimbochromis
- Scientific name: Nimbochromis polystigma
Habitat
Endemic to Lake Malawi, where it inhabits sandy bays, sediment-rich flats and the sand-rock interface of the open lake. The water is hard and alkaline (pH 7.8-8.6, KH 6-15) and warm year round; large adults forage across open sand and through rock outcrops.
Tank requirements
- Minimum tank volume: 500 L (132.1 US gal)
- Adult size: 20-25 cm
- Temperature: 24-27 °C (75-81 °F)
- pH: 7.8-8.6
- GH: 10-20 °dGH
- Water flow: medium
- Lifespan: 8-12 years
Diet
In the wild a carnivore or specialised feeder depending on species — many haps eat small fish, invertebrates or sift sand for hidden prey. In aquaria a moderate-protein cichlid pellet supplemented with frozen krill, mysis and chopped earthworm maintains condition and colour; vegetable matter is not the main component as it is for mbuna.
Compatibility
Less aggressive but larger than mbuna; best kept in spacious 350+ L tanks with one male and several females, alongside other peaceful Malawi haps and peacocks. Avoid mixing with rock-dwelling mbuna, whose constant aggression suppresses these larger fish, and avoid similar-coloured congeners to prevent hybridisation.
Breeding
A polygamous maternal mouthbrooder. The male defends a sand "scrape" or a small territory near a rock, displays his nuptial colours and entices females to spawn; the female collects the eggs into her mouth and incubates them for about three weeks before releasing fry.
Conservation status
IUCN Red List: see species page. Most haps are widely distributed in Lake Malawi and assessed as Least Concern; localised forms with narrow ranges are more vulnerable to environmental change.
Nimbochromis polystigma Breeding Guide
Overview
Nimbochromis polystigma is a piscivorous haplochromine cichlid endemic to Lake Malawi, preferring areas with rock and sand substrate or plentiful vegetation. It grows to 23 cm (9.1 in) in the wild and up to 30 cm (12 in) in aquaria, and often preys on juvenile cichlids. It is a notable ambush predator that uses thanatosis, lying motionless on the bottom, sometimes on its side as if feigning death, until small fish approach, then pouncing; its colour fades during this behaviour, apparently because the whiter colour attracts more small cichlids.
Sexing
The species is sexually dimorphic. Adult males develop breeding coloration that differs from females and juveniles; in this species males show a blue head when in breeding condition, while females and immature fish retain the creamy, dark-blotched pattern.
Conditioning
As a piscivore that ambushes prey, broodstock should be conditioned on a meaty, protein-rich diet. Stable, firm, alkaline rift-lake water supports conditioning. Provide cover such as rock or vegetation matching its natural ambush habitat, since in the wild the species also uses disruptive camouflage to launch ambush attacks on small fish from the cover of vegetation. Well-fed adults are less likely to harass each other, which helps a male and his females remain settled enough to spawn.
Breeding Setup
Because of its adult size and predatory nature, this species needs a large aquarium of at least 300 litres (80 US gal). It is best spawned with a single male and a group of females over an open substrate with rock and planted cover, so courtship pursuits are spread across several females.
Spawning Behaviour & Trigger
Like most Lake Malawi cichlids, Nimbochromis polystigma is a mouthbrooder. A receptive female lays eggs that the male fertilises, after which she takes them into her mouth to incubate.
Egg & Fry Care
The female carries her young in her mouth for two to three weeks before they are released. Because the adults are predatory, free-swimming fry are vulnerable in a community setting and are best reared separately on suitably sized foods.
Common Challenges
The principal challenges are housing a large predatory cichlid that may eat smaller tankmates and protecting released fry from predation. As with all maternal mouthbrooders, the holding female stops feeding during incubation, so good conditioning beforehand is important.