Compatibility Overview
Harlequin Rasbora and Julii Cory can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 40-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Harlequin Rasbora | Julii Cory | Verdict |
|---|---|---|---|
| Temperature | 72–81°F | 72–79°F | ✅ 72–79°F |
| pH Range | 5.5–7.5 | 6.0–7.0 | ✅ 6.0–7.0 |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 1.75 in | 1.2 in | ✅ Similar |
| Min. Group | 8+ | 1+ | See below |
| Min. Tank Size | 40 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Harlequin Rasbora — Trigonostigma heteromorpha
Active mid-level schooling fish with a distinctive black triangular patch. One of the best all-around community tank fish.
→ Full Harlequin Rasbora care guide
Julii Cory — Aquarium species
The Julii Cory is a popular, peaceful bottom-dweller that thrives in community tanks. With a lifespan of up to 5 years, they are suitable for beginners and experienced aquarists alike. These fish are known for their dark brown coloration with distinctive white spots and a slender, flat body shape. They are moderately active and prefer a well-planted tank wit
Frequently Asked Questions
Can Harlequin Rasbora live with Julii Cory?
Yes, in a well-planned setup. Harlequin Rasbora and Julii Cory can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 40-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Harlequin Rasbora and Julii Cory together?
A minimum of 40 gallons is recommended for keeping Harlequin Rasbora and Julii Cory together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Harlequin Rasbora and Julii Cory?
72–79°F
Is a Harlequin Rasbora aggressive toward a Julii Cory?
Harlequin Rasbora is peaceful and Julii Cory is semi. No major aggression issues are expected between these species.
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 | 100/100 |
| Ph | 100/100 |
| Temperament | 75/100 |
| Adult Size | 100/100 |
| Swim Zone | 92/100 |
| 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 | 40 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 55 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 90 gal | Best when keeping larger schools or reducing territorial pressure. |