Can Altum Angel and Boeseman's Rainbowfish Live Together?

Altum Angel is a moderately assertive species (5/10), while Boeseman's Rainbowfish is peaceful (2/10). This modest difference means Altum Angel may occasionally assert dominance over Boeseman's Rainbowfish.

Altum Angel and Boeseman's Rainbowfish 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.

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

The safe temperature window for both species falls between 27°C and 30°C. Aim for the midpoint of this range (around 28.5°C) for optimal comfort.

The pH requirements of Altum Angel (4.5–6.5) and Boeseman's Rainbowfish (7–8.1) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Altum Angel needs 1–5 dGH while Boeseman's Rainbowfish requires 9–19 dGH.

To house Altum Angel and Boeseman's Rainbowfish together, plan for an aquarium of at least 400 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: Sand (Sifters), Driftwood (Digestion/Hiding), Leaf Litter/Blackwater, Plants - Floating, Plants - lighly covered. Meeting these requirements will help both species thrive.

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

Altum Angel and Boeseman's Rainbowfish 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. Boeseman's Rainbowfish is an aggressive eater that may prevent Altum Angel from getting enough food.

Because Boeseman's Rainbowfish is a fast, competitive feeder, consider using sinking pellets or feeding at opposite ends of the setup to ensure Altum Angel receives an adequate share.