Can Discus and Least Killifish (Heterandria) Live Together?
Discus and Least Killifish (Heterandria) are not recommended as tank mates due to no temperature overlap. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.
At a Glance
Behaviour & Temperament
Discus is a generally mild-mannered species (4/10), while Least Killifish (Heterandria) is peaceful (1/10). This modest difference means Discus may occasionally assert dominance over Least Killifish (Heterandria).
Discus and Least Killifish (Heterandria) both frequent the Middle (Open Water) and Bottom (Substrate) 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.
Water Parameters
There is no temperature overlap between Discus (28–32°C) and Least Killifish (Heterandria) (18–27°C). This fundamental mismatch makes long-term cohabitation impractical.
Both fish can tolerate a pH between 7 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.
For general hardness, the shared comfort zone is 5–12 dGH. Regular testing will ensure conditions stay within this range. An aquarium test kit is recommended for monitoring.
Tank Setup
To house Discus and Least Killifish (Heterandria) together, plan for an aquarium of at least 300 litres with a minimum length of 120 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.
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.
Find the right tank equipment
Browse tanks, décor, and equipment suited for this setup.
Diet & Feeding
Feeding time deserves special attention with this pairing. Discus is a known shrimp eater and may prey on small invertebrates or nano fish like Least Killifish (Heterandria).
Frequently Asked Questions
Can Discus and Least Killifish (Heterandria) live together?▾
No. This combination is not recommended. Key incompatibilities — such as non-overlapping temperature ranges — make cohabitation unsafe.
What size tank do Discus and Least Killifish (Heterandria) need?▾
A minimum of 300 litres (tank length at least 120 cm) is recommended. This provides enough space for both species to establish their own areas and reduces the likelihood of territorial disputes.
What water temperature is best for Discus and Least Killifish (Heterandria) together?▾
Unfortunately, there is no temperature range that satisfies both species. Discus requires 28–32°C, while Least Killifish (Heterandria) needs 18–27°C.
Are Discus or Least Killifish (Heterandria) aggressive?▾
Discus is generally mild-mannered (4/10) and Least Killifish (Heterandria) is peaceful (1/10). Their similar temperaments generally lead to a peaceful coexistence.
What pH do Discus and Least Killifish (Heterandria) need?▾
Both species overlap in the 7–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.
How do I manage Discus's territorial behaviour?▾
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Discus space to claim a territory without encroaching on the other fish's area. Adding décor that divides the tank into distinct zones works especially well.
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