Compatibility Overview
Royal Gramma and Swordtail 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 | Royal Gramma | Swordtail | Verdict |
|---|---|---|---|
| Temperature | 73–81°F | 65–80°F | ✅ 73–80°F |
| pH Range | 8.0–8.5 | 7.0–8.3 | ⚠️ 8.0–8.3 (narrow) |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 1.6 in | 5 in | ⚠️ 3.1× difference |
| Min. Group | 1+ | 3+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Royal Gramma — Aquarium species
The Royal Gramma, known for its vibrant blue coloration, is a popular saltwater fish among beginners and experienced aquarists alike. It requires a well-maintained tank with plenty of swimming space and a moderate current. With a peaceful temperament and a relatively easy care routine, the Royal Gramma can be a great addition to a community tank. Its delicat
→ Full Royal Gramma care guide
Swordtail — Xiphophorus hellerii
Hardy livebearer with a distinctive elongated lower tail fin in males. Peaceful community fish that tolerate a wide temperature range.
Frequently Asked Questions
Can Royal Gramma live with Swordtail?
Generally not recommended. Royal Gramma and Swordtail 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 Royal Gramma and Swordtail together?
A minimum of 55 gallons is recommended for keeping Royal Gramma and Swordtail together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Royal Gramma and Swordtail?
73–80°F
Is a Royal Gramma aggressive toward a Swordtail?
Royal Gramma is semi and Swordtail 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 | 88/100 |
| Ph | 60/100 |
| 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 | 55 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 75 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 125 gal | Best when keeping larger schools or reducing territorial pressure. |