Can Discus and Lyretail Killifish Live Together?

Discus is a generally mild-mannered species (4/10), while Lyretail Killifish is generally mild-mannered (3/10). This modest difference means Discus may occasionally assert dominance over Lyretail Killifish.

Discus and Lyretail Killifish 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: Shrimp eaters may also prey on very small nano fish.

Worth noting: Lyretail Killifish is a known jumper, so a tight-fitting lid is essential.

There is no temperature overlap between Discus (28–32°C) and Lyretail Killifish (21–26°C). This fundamental mismatch makes long-term cohabitation impractical.

Both fish can tolerate a pH between 5.5 and 7. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 1–10 dGH. Regular testing will ensure conditions stay within this range.

To house Discus and Lyretail Killifish together, plan for an aquarium of at least 250 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 - Densely covered, Plants - Floating. 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.

Discus and Lyretail Killifish 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. Discus is a known shrimp eater and may prey on small invertebrates or nano fish like Lyretail Killifish.