๐Ÿ  Fish Compatibility Guide

Can Black Ghost Knifefish and Keyhole Cichlid Live Together?

Updated September 23, 2026 ยท FishCare AI Editorial Team

โŒ Not Compatible โ€” Compatibility Score: 32/100
32/100 โ€” Not Compatible

Black Ghost Knifefish and Keyhole Cichlid Compatibility Overview

Black Ghost Knifefish and Keyhole Cichlid are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Review the behavior and water details before deciding whether to attempt the pairing.

Compatibility factors for Black Ghost Knifefish and Keyhole Cichlid
FactorBlack Ghost KnifefishKeyhole CichlidVerdict
Temperature73โ€“82ยฐF70โ€“82ยฐFโœ… 73โ€“82ยฐF
pH Range6.0โ€“8.04.0โ€“7.5โœ… 6.0โ€“7.5
Temperamentsemipeacefulโš ๏ธ Monitor
Adult Size18.0 in4.3 inโŒ 4ร— difference
Min. Group1+2+See below
Min. Tank Size100 gallons (for both species)โ€”

Compatibility Positives

A stable shared temperature range is available.
Their pH requirements overlap.
Temperament risk is relatively low when normal group sizes are maintained.

Incompatibility Reasons

The adult size gap creates a meaningful predation risk.

Species Profiles

Black Ghost Knifefish โ€” Apteronotus albifrons

Black Ghost Knifefish and Keyhole Cichlid compatibility โ€” Black Ghost Knifefish

The Black Ghost Knifefish is a unique and elegant addition to the aquarium. With a lifespan of 5-8 years, it requires a minimum tank size of 200 liters. It is a solitary fish with a low aggression level and moderate activity. Its slender body and silver-blue coloration make it a captivating sight.

โ†’ Full Black Ghost Knifefish care guide

Keyhole Cichlid โ€” Cleithracara maronii

Black Ghost Knifefish and Keyhole Cichlid compatibility โ€” Keyhole Cichlid

The Keyhole Cichlid is a popular choice for beginners due to its relatively easy care and peaceful temperament. These fish are known for their distinct keyhole marking and vibrant coloration. They do well in a community tank with other peaceful species, but should be provided with plenty of hiding spots to feel secure.

โ†’ Full Keyhole Cichlid care guide

Frequently Asked Questions

Can Black Ghost Knifefish live with Keyhole Cichlid?

Generally not recommended. Black Ghost Knifefish and Keyhole Cichlid are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Review the behavior and water details before deciding whether to attempt the pairing.

What tank size do I need for Black Ghost Knifefish and Keyhole Cichlid together?

A minimum of 100 gallons is recommended for keeping Black Ghost Knifefish and Keyhole Cichlid together. A larger tank improves water stability and reduces territorial conflict.

What temperature suits both Black Ghost Knifefish and Keyhole Cichlid?

73โ€“82ยฐF โ€” inside Black Ghost Knifefish's 73โ€“82ยฐF and Keyhole Cichlid's 70โ€“82ยฐF.

Is a Black Ghost Knifefish aggressive toward a Keyhole Cichlid?

The adult size gap creates a meaningful predation risk.

Related Compatibility Guides

Tank Size for Black Ghost Knifefish and Keyhole Cichlid

Use the scenario that matches the actual group sizes and temperament you plan to keep.

ScenarioTankWhen it applies
Minimum viable100 galOnly for the recommended minimum groups, mature filtration, and close monitoring.
Recommended community150 galAdds territory, swimming room, and a safer buffer for behavior.
Low-conflict setup180 galBest when keeping larger schools or reducing territorial pressure.