Can Cardinal Tetra and Sixbar Distichodus Live Together?

Cardinal Tetra is a peaceful species (1/10), while Sixbar Distichodus is semi-aggressive (7/10). This notable difference means Sixbar Distichodus may occasionally assert dominance over Cardinal Tetra.

Large aggression gap (6 points) between Cardinal Tetra and Sixbar Distichodus increases stress risk for the more peaceful fish.

Cardinal Tetra and Sixbar Distichodus 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.

Worth noting: Sixbar Distichodus is a known jumper, so a tight-fitting lid is essential.

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 6 and 7. Maintaining a stable value within this band is more important than hitting an exact number.

Hardness requirements are incompatible: Cardinal Tetra needs 1–8 dGH while Sixbar Distichodus requires 10–20 dGH.

To house Cardinal Tetra and Sixbar Distichodus together, plan for an aquarium of at least 1000 litres with a minimum length of 200 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: Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Plants - Densely covered, Sand (Sifters), Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Sixbar Distichodus is a plant destroyer, which conflicts with Cardinal Tetra'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.

Cardinal Tetra and Sixbar Distichodus 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.