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Encyclopedia / African Cichlids / Black pearl
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Variations

3 kinds · tap one for a closer look

Black pearl

Altolamprologus calvus · Altolamprologus calvus, Calvus, Black calvus, Pearl calvus

Predatory toward small fish and fry; peaceful toward larger tank-mates.

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14 cmAdult size ✓
24–27 °CTemperature ✓
8–9pH ✓
172 LSmallest tank ✓
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Tank mates
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Not recommended
  • Black pearl eats animals up to about 5 cm. Neon tetra only grows to 2.5 cm.
  • Rift lake cichlids like black pearl need hard, alkaline water and a busy, cichlid-only tank.
Not recommended
  • Black pearl eats animals up to about 5 cm. Cardinal tetra only grows to 3 cm.
  • Rift lake cichlids like black pearl need hard, alkaline water and a busy, cichlid-only tank.
Not recommended
  • Black pearl eats animals up to about 5 cm. Black neon tetra only grows to 3.2 cm.
  • Rift lake cichlids like black pearl need hard, alkaline water and a busy, cichlid-only tank.
With conditions
  • Rift lake cichlids like black pearl need hard, alkaline water and a busy, cichlid-only tank.
  • Their pH needs don't quite meet (8–9 vs 6–7.5). Aim between the two and keep it steady.
With conditions
  • Rift lake cichlids like black pearl need hard, alkaline water and a busy, cichlid-only tank.
  • Only a narrow pH range suits both: exactly 8.
Compatible
Compatible
Compatible
Compatible
Compatible

65 species in our list are a good match.

Facts checked against sources on 16 Oct 2026. ✓ means a source backs it; ? means no reliable source yet. See sources

Care and water

Hardness ✓8–20 dGH
Group size ✓2 or more
Temperament ✓Semi-aggressive
Swims at ?All levels
Care level ✓Moderate
Diet Carnivore
Lifespan ?Unknown
Size in shops 4–7 cm
Growth Medium

Behavior

Predatory toward small fish and fry; peaceful toward larger tank-mates.

  • cave

Food

Frozen mysis, krill and small pellets; live foods where possible.

Tap a food to see what it is.

Male or female

Males grow larger and have longer fins than females.

Health

Common problems. Tap one to see the signs. This is a guide, not a diagnosis.

Breeding

Cave spawner (pair bond) · Moderate

Cave spawner; the female guards the eggs, which number about 200.

Pairing

Buy a group of 6 and let a pair form, or buy a proven pair; keep a pair per tank to avoid fights.

Setup

100-150 L tank with rock piles creating narrow caves and slits, hard alkaline water (pH 8-9) and strong filtration.

What starts it

Stable pair bond, good conditioning and a cave that fits the female.

Eggs

Up to about 200 eggs; they hatch in about 2 days and the fry are free-swimming 8-10 days later.

Raising the fry

Fry hide in the cave and become free swimming after a week. Feed microworms and newly hatched brine shrimp; parents tolerate and often protect them.

Common mistakes
  • Mixing several pairs in a small tank
  • Giving caves that are too big
  • Using soft water
Full breeding guide, day-by-day plan and simulator →

Where it lives in the wild

RegionLake Tanganyika – southern and western shores
Rivers and lakesLake Tanganyika (Zambia & DR Congo coasts)
HabitatRocky slopes with crevices
Native rangeAbout 200 km across
See it on the world map

The story of the black pearl

A deep, very flat-bodied Lake Tanganyika cichlid that slips into narrow cracks and small caves to hunt, feeding mainly on shrimps and other crustaceans. Described by Poll in 1978.

Max Poll described this fish in 1978, originally in Lamprologus. Its very thin body lets it slip into crevices to hunt young fish and eggs. Black and spotted forms are especially sought after.

First described by Max Poll in 1978.

  • Its body is so narrow it can reach into rock gaps other predators cannot.
  • Females are much smaller than males and spawn in small holes or shells.
  • Its scales are sharp-edged, helping protect it from attack.

Sources

15 facts checked with sources