Compatibility Overview
Goldfish and Guppy 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 | Guppy | Verdict |
|---|---|---|---|
| Temperature | 50–74°F | 72–82°F | ⚠️ 72–74°F (narrow) |
| pH Range | 6.5–8.0 | 6.8–8.5 | ✅ 6.8–8.0 |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 12 in | 2.5 in | ❌ 5× 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.
Guppy — Poecilia reticulata
Hardy and colourful livebearers. Males' long flowing tails make them targets for fin-nipping species. Very prolific breeders.
Frequently Asked Questions
Can Goldfish live with Guppy?
Generally not recommended. Goldfish and Guppy 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 Guppy together?
A minimum of 100 gallons is recommended for keeping Goldfish and Guppy together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Goldfish and Guppy?
72–74°F (narrow)
Is a Goldfish aggressive toward a Guppy?
Goldfish is peaceful and Guppy is peaceful. Goldfish requires cold water; Guppy requires tropical water. These environments are incompatible.