Guppy and Molly Compatibility
Guppy and Molly make a good match: temperature ranges overlap at 72–82°F, water chemistry aligns, and neither presents a meaningful behavioural or size risk. Plan on at least 20 gallons. Individual fish vary — observe behaviour during introduction.
Guppy vs Molly at a glance
Why this verdict
- Temperature: Shared range of 72–82°F.
- Water parameters: Shared pH range of 7.5–7.8.
- Temperament: Both species are peaceful community fish.
- Adult size: Comparable adult sizes (~1.8" and ~3.5").
- Swimming zone: Complementary layers (top + middle) reduce competition for space.
- Schooling: Group sizes matter: Guppy: keep at least 3; Molly: keep at least 3.
- Tank size: Plan for at least 20 gallons to satisfy both species.
Main risks
- Both are peaceful livebearers with overlapping temperature and pH preferences.
- Mollies prefer harder water; keep pH toward the upper guppy range.
Recommended tank
Plan on 20 gallons or larger for this pair. Suitable sizes: 20 gallon High, 20 gallon Long, 29 gallon.
Group sizes: Guppy: keep at least 3; Molly: keep at least 3.
Sources
- FishBase — Scientific Database · Primary / scientific · https://www.fishbase.se/
- SeriouslyFish — Specialist Publication · High authority · https://www.seriouslyfish.com/
- Aquarium Forge editorial guidelines — Editorial Interpretation · Editorial interpretation
- FishBase — Scientific Database · Primary / scientific · https://www.fishbase.se/
- SeriouslyFish — Specialist Publication · High authority · https://www.seriouslyfish.com/
- Aquarium Forge editorial guidelines — Editorial Interpretation · Editorial interpretation
- Aquarium Forge editorial guidelines — Editorial Interpretation · Editorial interpretation
Compatibility verdicts are planning guidance, not guarantees — individual fish vary. Rule version 1.1 · Data reviewed: .
Frequently asked questions
Can Guppy and Molly live together?
Our verdict is “Good Match”. Guppy and Molly make a good match: temperature ranges overlap at 72–82°F, water chemistry aligns, and neither presents a meaningful behavioural or size risk. Plan on at least 20 gallons. Individual fish vary — observe behaviour during introduction.
What tank size do Guppy and Molly need?
Plan for at least 20 gallons so both species have their minimum space — Guppy needs 10+ gal and Molly needs 20+ gal. Adding length and cover reduces stress further.
What temperature do Guppy and Molly share?
Their comfortable ranges overlap at 72–82°F. Hold the tank near the middle of that band and avoid the extremes of either species' range.
What are the main risks keeping Guppy with Molly?
Both are peaceful livebearers with overlapping temperature and pH preferences. Mollies prefer harder water; keep pH toward the upper guppy range.
How many Guppy and Molly should I keep?
Guppy: keep at least 3; Molly: keep at least 3. Group sizes matter for shoaling fish — too few and they become stressed and nippy.
Canonical https://aquariumforge.com/compatibility/guppy/molly/