Can killifish live with swordtails?

Verdict

Yes, with care

Yes, with care. Killifish and swordtails can share a tank, but watch one thing. Water chemistry is a squeeze. The only pH that suits both is around 7.

Killifish70–77°F · pH 5.5–7

Swordtail72–79°F · pH 7–8.3

What to watch

Watch outWater chemistry is a squeeze. The only pH that suits both is around 7.

What works

Both are fine at 72–77°F.
They use different parts of the tank: killifish the top, swordtails the mid.

Water side by side

The green band is the temperature range both can live in.

The green band is the pH both tolerate.

Size to scale

Adult length in an aquarium. A fish can swallow anything that fits in its mouth, roughly a third to half its own length for predators.

Care at a glance

	Killifish	Swordtail
Temperature	70–77 °F	72–79 °F
pH	5.5–7	7–8.3
Adult size	2.5 in	5.0 in
Minimum tank	10 gal	30 gal
Temperament	Peaceful	Semi-aggressive
Swims at	Top	Middle
Group	Alone or in pairs	Groups of 3+
Diet	Carnivore	Omnivore

Better tank mates for killifish

All killifish tank mates

Better tank mates for swordtails

All swordtail tank mates

Questions

Can killifish live with swordtails?

Yes, with care. Killifish and swordtails can share a tank, but watch one thing. Water chemistry is a squeeze. The only pH that suits both is around 7.

What temperature suits both killifish and swordtails?

72–77 °F. Killifish need 70–77 °F, swordtails need 72–79 °F.

What size tank do killifish and swordtails need together?

At least 30 gal, set by the swordtail. Add space for each extra fish.