Can mollies live with swordtails?

Verdict
Yes

Yes. Mollies and swordtails get along in the same tank. Both are fine at 72–79°F. Plan on at least 30 gal.

MollyMolly72–82°F · pH 7.5–8.5 SwordtailSwordtail72–79°F · pH 7–8.3

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–79°Molly 72–82°Swordtail 72–79°
The green band is the temperature range both can live in.
456789Both: 7.5–8.3Molly 7.5–8.5Swordtail 7–8.3
The green band is the pH both tolerate.

Size to scale

Molly · 4 inSwordtail · 5 in0"1"2"3"4"5"6"
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

MollySwordtail
Temperature72–82 °F72–79 °F
pH7.5–8.57–8.3
Adult size4.0 in5.0 in
Minimum tank20 gal30 gal
TemperamentPeacefulSemi-aggressive
Swims atTopMiddle
GroupGroups of 3+Groups of 3+
DietOmnivoreOmnivore

Better tank mates for mollies

All molly tank mates

Better tank mates for swordtails

All swordtail tank mates

Questions

Can mollies live with swordtails?

Yes. Mollies and swordtails get along in the same tank. Both are fine at 72–79°F. Plan on at least 30 gal.

What temperature suits both mollies and swordtails?

72–79 °F. Mollies need 72–82 °F, swordtails need 72–79 °F.

What size tank do mollies and swordtails need together?

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