Can Least Killifish (Heterandria) and Mbu Puffer Live Together?

Least Killifish (Heterandria) is a peaceful species (1/10), while Mbu Puffer is semi-aggressive (7/10). This notable difference means Mbu Puffer may occasionally assert dominance over Least Killifish (Heterandria).

Large aggression gap (6 points) between Least Killifish (Heterandria) and Mbu Puffer increases stress risk for the more peaceful fish.

Least Killifish (Heterandria) and Mbu Puffer 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.

There is a critical concern: the Nano / Bite-sized (Predation Risk) behaviour of one fish directly conflicts with the Piscivore (Eats small/nano fish) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Additional behavioural considerations to keep in mind: Aggressive fish may bully and stress shy, slow-moving species. Aggressive eaters may outcompete shy fish for food, leading to malnutrition.

The safe temperature window for both species falls between 24°C and 27°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

Both fish can tolerate a pH between 7 and 8. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 10–20 dGH. Regular testing will ensure conditions stay within this range.

To house Least Killifish (Heterandria) and Mbu Puffer together, plan for an aquarium of at least 1500 litres with a minimum length of 240 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: Plants - Densely covered, Plants - Floating, Sand (Sifters), Shells (Breeding/Hiding), Smooth Gravel (Sensitive Barbels). 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.

Feeding time deserves special attention with this pairing. Mbu Puffer is an aggressive eater that may prevent Least Killifish (Heterandria) from getting enough food.

Because Mbu Puffer is a fast, competitive feeder, consider using sinking pellets or feeding at opposite ends of the setup to ensure Least Killifish (Heterandria) receives an adequate share.