Compatibility Overview
Discus 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 | Discus | Swordtail | Verdict |
|---|---|---|---|
| Temperature | 82–88°F | 65–80°F | ❌ No overlap |
| pH Range | 5.0–7.0 | 7.0–8.3 | ⚠️ 7.0–7.0 (narrow) |
| Temperament | semi | peaceful | ⚠️ Monitor |
| Adult Size | 8 in | 5 in | ✅ Similar |
| Min. Group | 5+ | 3+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Discus — Symphysodon spp.
The 'king of the aquarium' — beautiful but demanding. Requires very warm, soft, acidic water that excludes most community fish.
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 Discus live with Swordtail?
Generally not recommended. Discus 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 Discus and Swordtail together?
A minimum of 100 gallons is recommended for keeping Discus and Swordtail together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Discus and Swordtail?
No overlap
Is a Discus aggressive toward a Swordtail?
Discus is semi and Swordtail is peaceful. Temperature ranges do not overlap: Discus needs 82–88°F; Swordtail needs 65–80°F.