Can Molly (Sailfin/Black/Dalmatian) and Peacock Gudgeon Live Together?

Molly (Sailfin/Black/Dalmatian) is a generally mild-mannered species (3/10), while Peacock Gudgeon is peaceful (2/10). This modest difference means Molly (Sailfin/Black/Dalmatian) may occasionally assert dominance over Peacock Gudgeon.

Molly (Sailfin/Black/Dalmatian) and Peacock Gudgeon both frequent the Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion. Aggressive eaters may outcompete shy fish for food, leading to malnutrition.

The safe temperature window for both species falls between 24°C and 26°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

Hardness requirements are incompatible: Molly (Sailfin/Black/Dalmatian) needs 12–30 dGH while Peacock Gudgeon requires 5–10 dGH.

To house Molly (Sailfin/Black/Dalmatian) and Peacock Gudgeon together, plan for an aquarium of at least 75 litres with a minimum length of 60 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Plants - Densely covered, Established Algae (Otocinclus), Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Molly (Sailfin/Black/Dalmatian) and Peacock Gudgeon are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.

Feeding time deserves special attention with this pairing. Molly (Sailfin/Black/Dalmatian) is an aggressive eater that may prevent Peacock Gudgeon from getting enough food.

Because Molly (Sailfin/Black/Dalmatian) is a fast, competitive feeder, consider using sinking pellets or feeding at opposite ends of the setup to ensure Peacock Gudgeon receives an adequate share.