Keyhole cichlid

Quick facts

Adult size

10 cm

Lifespan

can live up to 10 years

Tank zone

mid

Temperament

peaceful

Difficulty

beginner

Water parameters

Temperature

22–28°C

pH

6.0 to 8.0

Hardness

1 to 18 dGH

Tank requirements

Minimum volume

150 L

Minimum length

90 cm

Flow

low

Lighting

dim preferred

Substrate

fine

Driftwood

preferred

Hiding spots

needed

Feeding

Diet: omnivore, feeds primarily at the mid.

Omnivore that accepts most foods without complaint. Pellets, flake, frozen bloodworm, frozen brine shrimp, frozen daphnia, live blackworms, and blanched vegetables. They feed from the bottom and midwater, methodically picking through substrate and surfaces. Not competitive at feeding time; in tanks with assertive species they may hang back and miss out. Targeted feeding or after-lights-out feeding helps if competition is an issue. Feed twice daily. Live food brings out richer body color and encourages breeding behavior.

Compatibility

• The calmest cichlid in the hobby. Keyholes are so non-aggressive that they lose territorial disputes to tetras. A breeding pair defends its spawn site but does so with half-hearted chasing rather than real combat.
• Genuinely suitable for community tanks with peaceful species: tetras, rasboras, corydoras, otocinclus, and dwarf gouramis. They occupy the lower and middle water column and mostly ignore tankmates.
• Stress-sensitive despite being hardy in terms of water chemistry. Loud noises, aggressive tankmates, or frequent tank disturbances cause them to hide, lose color, and refuse food. They need a calm environment.
• Pairs bond and often stay together long-term. They display interesting parental behavior without the tank-destroying aggression that comes with most cichlid breeding.

Habitat

Native to slow-moving, heavily vegetated waterways in Trinidad, Tobago, Guyana, Suriname, and the delta region of the Orinoco basin. Found in tannin-stained streams and swamps with leaf litter, submerged wood, and dense bank vegetation. The water is soft and acidic. The species (Cleithracara maronii) was described by Steindachner in 1881 and has been in the hobby since the early 20th century. The common name refers to a dark keyhole-shaped marking on the flank, which varies in intensity and shape between individuals. Body color is a warm yellow-beige to olive-brown with faint dark bars that appear and disappear depending on mood. When stressed or frightened, the body darkens dramatically and a broad black band appears from the eye to the caudal peduncle. When relaxed, the fish lightens to a warm tan. This rapid color-change ability is the best real-time stress indicator of any commonly kept cichlid. Males are slightly larger (10–12 cm) with more extended dorsal and anal fin points; females are smaller (8–10 cm) and rounder. All stock is tank-bred. Not expensive, but not always in stock at general pet stores since demand is lower than flashier cichlids.

Breeding

Substrate spawner. A pair selects a sheltered surface (underside of a rock, inside a cave, broad leaf) and deposits 100-300 adhesive eggs. Both parents guard the clutch, but aggression toward other fish is minimal compared to any other cichlid. They more often position themselves between the threat and the eggs rather than charging. Eggs hatch in 3-4 days. Fry become free-swimming 4-5 days later and are herded gently by both parents. Parental care lasts 3-6 weeks. Fry eat baby brine shrimp and microworms from the start. Keyhole cichlids are easily spooked during breeding; too much tank traffic or maintenance can cause them to eat the eggs or abandon the brood. A calm, low-traffic location for the tank improves breeding success. Spawning frequency is lower than prolific species like convicts; expect a brood every 6-10 weeks in good conditions.

Common problems

Stress response is the main management issue. Keyholes darken, hide, and stop eating when conditions aren't right. Common stressors: aggressive tankmates, overly bright lighting without cover, sudden movements near the tank, and frequent netting or tank maintenance. The fix is always environmental: calm tankmates, floating plants for cover, dim lighting, and minimal disturbance. In the right setup, they're relaxed and visible all day. Health problems are uncommon in stable water. Ich can appear in newly purchased fish; treat with temperature elevation. The species tolerates a fairly wide parameter range (pH 6.0-7.5, temperature 22–28°C) despite coming from soft acidic water in the wild. Tank-bred stock is more adaptable than wild-caught. Lifespan is 8-10 years.

Bioload

Bioload coefficient: 2.6 (moderate-sized peaceful cichlid; similar per-cm to a kribensis).

Bioload coefficients are calibrated against the neon tetra as the anchor (1.0). See the methodology page for the formula and how each value was derived.

Further reading

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