๐Ÿ  Fish Compatibility Guide

Can Molly and Royal Gramma Live Together?

Updated September 23, 2026 ยท FishCare AI Editorial Team

โŒ Not Compatible โ€” Compatibility Score: 0/100
0/100 โ€” Not Compatible

Molly and Royal Gramma Compatibility Overview

Molly and Royal Gramma are generally not recommended to be housed together. One of these is a marine species and the other is not; they cannot share one aquarium. Their usable pH overlap is narrow and requires stable, tested water. Review the behavior and water details before deciding whether to attempt the pairing.

Compatibility factors for Molly and Royal Gramma
FactorMollyRoyal GrammaVerdict
Temperature72โ€“82ยฐF72โ€“82ยฐFโœ… 72โ€“82ยฐF
pH Range7.5โ€“8.58.1โ€“8.4โš ๏ธ 8.1โ€“8.4 (narrow)
Temperamentpeacefulsemiโš ๏ธ Monitor
Adult Size4 in3.0 inโœ… Similar
Min. Group3+1+See below
Min. Tank Size55 gallons (for both species)โ€”

Compatibility Positives

A stable shared temperature range is available.
Temperament risk is relatively low when normal group sizes are maintained.

Incompatibility Reasons

One of these is a marine species and the other is not; they cannot share one aquarium.
Their usable pH overlap is narrow and requires stable, tested water.

Species Profiles

Molly โ€” Poecilia sphenops

Molly and Royal Gramma compatibility โ€” Molly

Hardy livebearers that prefer alkaline, hard water โ€” sometimes slightly brackish. Prolific breeders; peaceful community fish.

โ†’ Full Molly care guide

Royal Gramma โ€” Gramma loreto

Molly and Royal Gramma compatibility โ€” Royal Gramma

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.

โ†’ Full Royal Gramma care guide

Frequently Asked Questions

Can Molly live with Royal Gramma?

Generally not recommended. Molly and Royal Gramma are generally not recommended to be housed together. One of these is a marine species and the other is not; they cannot share one aquarium. Their usable pH overlap is narrow and requires stable, tested water. Review the behavior and water details before deciding whether to attempt the pairing.

What tank size do I need for Molly and Royal Gramma together?

A minimum of 55 gallons is recommended for keeping Molly and Royal Gramma together. A larger tank improves water stability and reduces territorial conflict.

What temperature suits both Molly and Royal Gramma?

72โ€“82ยฐF โ€” inside Molly's 72โ€“82ยฐF and Royal Gramma's 72โ€“82ยฐF.

Is a Molly aggressive toward a Royal Gramma?

Molly is peaceful and Royal Gramma is semi. No major aggression issues are expected between these species.

Related Compatibility Guides

Tank Size for Molly and Royal Gramma

Use the scenario that matches the actual group sizes and temperament you plan to keep.

ScenarioTankWhen it applies
Minimum viable55 galOnly for the recommended minimum groups, mature filtration, and close monitoring.
Recommended community75 galAdds territory, swimming room, and a safer buffer for behavior.
Low-conflict setup125 galBest when keeping larger schools or reducing territorial pressure.