Nimbochromis polystigma Breeding Guide

Breeding Nimbochromis polystigma, a piscivorous ambush hap from Lake Malawi that hunts by feigning death and broods its young for two to three weeks.

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.