Compatibility Overview
Goldfish 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 | Goldfish | Swordtail | Verdict |
|---|---|---|---|
| Temperature | 50–74°F | 65–80°F | ✅ 65–74°F |
| pH Range | 6.5–8.0 | 7.0–8.3 | ✅ 7.0–8.0 |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 12 in | 5 in | ⚠️ 2.4× difference |
| Min. Group | 1+ | 3+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Goldfish — Carassius auratus
Classic pond and aquarium fish that prefer cool water. Heavy waste producers that require robust filtration. Will eat small fish and shrimp.
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 Goldfish live with Swordtail?
Generally not recommended. Goldfish 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 Goldfish and Swordtail together?
A minimum of 100 gallons is recommended for keeping Goldfish and Swordtail together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Goldfish and Swordtail?
65–74°F
Is a Goldfish aggressive toward a Swordtail?
Goldfish is peaceful and Swordtail is peaceful. Goldfish requires cold water; Swordtail requires tropical water. These environments are incompatible.