Compatibility Overview
Blue Tang and Harlequin Rasbora 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 | Blue Tang | Harlequin Rasbora | Verdict |
|---|---|---|---|
| Temperature | 75–81°F | 72–81°F | ✅ 75–81°F |
| pH Range | 8.1–8.4 | 5.5–7.5 | ❌ No overlap |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 5.9 in | 1.75 in | ⚠️ 3.4× difference |
| Min. Group | 1+ | 8+ | See below |
| Min. Tank Size | 75 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Blue Tang — Aquarium species
The Blue Tang is a popular saltwater fish known for its vibrant blue color and yellow stripes. These fish are generally peaceful and can be kept in a community tank with other non-aggressive species. They require a well-maintained, spacious tank with plenty of swimming space and hiding spots. Regular water changes and proper nutrition are essential for their
Harlequin Rasbora — Trigonostigma heteromorpha
Active mid-level schooling fish with a distinctive black triangular patch. One of the best all-around community tank fish.
Frequently Asked Questions
Can Blue Tang live with Harlequin Rasbora?
Generally not recommended. Blue Tang and Harlequin Rasbora 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 Blue Tang and Harlequin Rasbora together?
A minimum of 75 gallons is recommended for keeping Blue Tang and Harlequin Rasbora together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Blue Tang and Harlequin Rasbora?
75–81°F
Is a Blue Tang aggressive toward a Harlequin Rasbora?
Blue Tang is semi and Harlequin Rasbora is peaceful. These animals require different water types and cannot share one aquarium.
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 | 0/100 |
| Temperament | 75/100 |
| Adult Size | 38/100 |
| 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 | 75 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 125 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 150 gal | Best when keeping larger schools or reducing territorial pressure. |