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Encyclopedia / Cichlids / Jack Dempsey
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Variations

2 kinds · tap one for a closer look

Jack Dempsey

Rocio octofasciata · Electric blue jack dempsey, Jd

Aggressive predator; tankmates must be robust.

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25 cmAdult size ✓
22–28 °CTemperature ✓
6.5–8pH ✓
243 LSmallest tank ✓
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Tank mates
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Not recommended
  • Jack Dempsey eats animals up to about 8 cm. Neon tetra only grows to 2.5 cm.
Not recommended
  • Jack Dempsey eats animals up to about 8 cm. Cardinal tetra only grows to 3 cm.
Not recommended
  • Jack Dempsey eats animals up to about 8 cm. Black neon tetra only grows to 3.2 cm.
With conditions
  • Rift lake cichlids like peacock cichlid need hard, alkaline water and a busy, cichlid-only tank.
With conditions
  • Rift lake cichlids like frontosa need hard, alkaline water and a busy, cichlid-only tank.
  • Only a narrow pH range suits both: exactly 8.
Compatible
Compatible
Compatible
Compatible
Compatible

120 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 ✓5–20 dGH
Group size ?Can live alone
Temperament ✓Aggressive
Swims at ?Middle
Care level ✓Moderate
Diet Carnivore
Lifespan ✓8–15 years
Size in shops 3–5 cm
Growth Medium

Behavior

Aggressive predator; tankmates must be robust.

Food

Pellets, prawns, insects.

Tap a food to see what it is.

Male or female

Mature males have long, pointed tips on the dorsal and anal fins; females lack these. Both sexes darken almost to black when breeding.

Health

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

Breeding

Egg-layer (substrate spawner) · Moderate

Biparental substrate spawner: lays eggs on a flat rock or other cleaned surface, and both parents guard the eggs and young.

Pairing

Buy a group of 6 young fish and let them pair up.

Setup

A 55-75 gallon (200-280 L) tank with caves and a flat stone, 26-28 C.

What starts it

Warm water and heavy feeding. A pair will clean a flat surface.

Eggs

About 500-800 eggs per spawning; in aquaria they hatch in about 3 days at 26.6°C and the fry swim freely about 3 days later.

Raising the fry

Feed baby brine shrimp, then crushed pellets. Parents guard well. Separate when fry reach 3 cm.

Common mistakes
  • A tank too small
  • Pairing with a weak partner
  • Too much fighting
Full breeding guide, day-by-day plan and simulator →

Where it lives in the wild

RegionCentral America – Mexico to Honduras
Rivers and lakesAtlantic drainages from Mexico to Honduras
HabitatMurky, warm, slow waters
Native rangeAbout 600 km across
See it on the world map

The story of the jack dempsey

Named after Jack Dempsey (1895-1983), the American heavyweight boxer who was world champion for much of the 1920s, for its strong facial features and pugnacious nature. The electric blue form is an ornamental strain that tends to stay smaller.

C. Tate Regan described this cichlid in 1903. American aquarists nicknamed it after the boxer Jack Dempsey because of its bold, pugnacious temperament. A striking 'electric blue' form is now bred in captivity.

First described by C. Tate Regan in 1903. Named for Common name after the boxer Jack Dempsey, for its aggression.

  • Its common name refers to a famous boxer.
  • It changes colour with mood.
  • An 'electric blue' form is captive-bred.

Sources

16 facts checked with sources