Can Threadfin Rainbowfish and White Top Hara (Gallireya Reef) Live Together?

Threadfin Rainbowfish is a peaceful species (1/10), while White Top Hara (Gallireya Reef) is semi-aggressive (7/10). This notable difference means White Top Hara (Gallireya Reef) may occasionally assert dominance over Threadfin Rainbowfish.

Large aggression gap (6 points) between Threadfin Rainbowfish and White Top Hara (Gallireya Reef) increases stress risk for the more peaceful fish.

Threadfin Rainbowfish and White Top Hara (Gallireya Reef) 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: Aggressive fish may bully and stress shy, slow-moving species. Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: Threadfin Rainbowfish is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

The pH requirements of Threadfin Rainbowfish (5.5–7.5) and White Top Hara (Gallireya Reef) (7.8–8.6) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 10–12 dGH. Regular testing will ensure conditions stay within this range.

To house Threadfin Rainbowfish and White Top Hara (Gallireya Reef) together, plan for an aquarium of at least 254 litres with a minimum length of 120 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, Plants - Floating, Sand (Sifters), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: White Top Hara (Gallireya Reef) is a plant destroyer, which conflicts with Threadfin Rainbowfish's requirement for live plants. Compromise where possible or prioritise the more critical need.

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

Threadfin Rainbowfish and White Top Hara (Gallireya Reef) 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.