Compatibility Overview
Keyhole Cichlid and Oscar are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
| Factor | Keyhole Cichlid | Oscar | Verdict |
|---|---|---|---|
| Temperature | 72–79°F | 74–81°F | ✅ 74–79°F |
| pH Range | 7.0–8.0 | 6.0–8.0 | ✅ 7.0–8.0 |
| Temperament | semi | aggressive | ❌ Risk |
| Adult Size | 2.0 in | 14 in | ❌ 7× difference |
| Min. Group | 1+ | 1+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Keyhole Cichlid — Aquarium species
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. With proper care, they can live for sev
→ Full Keyhole Cichlid care guide
Oscar — Astronotus ocellatus
Intelligent but aggressive cichlids that will eat any fish small enough to fit in their mouth. Require large tanks (75+ gallons) and robust tank mates.
Frequently Asked Questions
Can Keyhole Cichlid live with Oscar?
Generally not recommended. Keyhole Cichlid and Oscar are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
What tank size do I need for Keyhole Cichlid and Oscar together?
A minimum of 100 gallons is recommended for keeping Keyhole Cichlid and Oscar together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Keyhole Cichlid and Oscar?
74–79°F
Is a Keyhole Cichlid aggressive toward a Oscar?
Keyhole Cichlid is semi and Oscar is aggressive. The adult size gap creates a meaningful predation risk.
Related Compatibility Guides
Compatibility score breakdown
The overall score is weighted across water chemistry, behavior, adult size, swimming zone, and social needs. A score is a planning aid—not a guarantee for individual fish.
| Factor | Score |
|---|---|
| Temperature | 71/100 |
| Ph | 100/100 |
| Temperament | 25/100 |
| Adult Size | 8/100 |
| Swim Zone | 68/100 |
| Social Needs | 92/100 |
Tank size scenarios
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 100 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 150 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 180 gal | Best when keeping larger schools or reducing territorial pressure. |