Can Altum Angel and Redtail Splitfin Live Together?

Altum Angel is a moderately assertive species (5/10), while Redtail Splitfin is moderately assertive (6/10). This modest difference means Redtail Splitfin may occasionally assert dominance over Altum Angel.

Altum Angel and Redtail Splitfin 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.

There is no temperature overlap between Altum Angel (27–32°C) and Redtail Splitfin (18–26°C). This fundamental mismatch makes long-term cohabitation impractical.

The pH requirements of Altum Angel (4.5–6.5) and Redtail Splitfin (7–8.5) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Altum Angel needs 1–5 dGH while Redtail Splitfin requires 10–25 dGH.

To house Altum Angel and Redtail Splitfin 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 - Densely covered, Established Algae (Otocinclus). 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 Redtail Splitfin 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.