Can discus live with swordtails?

Verdict
No

No. Discus and swordtails should not share a tank. No shared temperature. Discus need 82–88°F, swordtails need 72–79°F.

DiscusDiscus82–88°F · pH 5.5–7 SwordtailSwordtail72–79°F · pH 7–8.3

What to watch

Water side by side

55°60°65°70°75°80°85°90°Discus 82–88°Swordtail 72–79°
The ranges do not meet, so one of them would always be too warm or too cold.
456789Both: 7Discus 5.5–7Swordtail 7–8.3
The green band is the pH both tolerate.

Size to scale

Discus · 6 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

DiscusSwordtail
Temperature82–88 °F72–79 °F
pH5.5–77–8.3
Adult size6.0 in5.0 in
Minimum tank55 gal30 gal
TemperamentPeacefulSemi-aggressive
Swims atMiddleMiddle
GroupGroups of 5+Groups of 3+
DietCarnivoreOmnivore

Better tank mates for discus

All discus tank mates

Better tank mates for swordtails

All swordtail tank mates

Questions

Can discus live with swordtails?

No. Discus and swordtails should not share a tank. No shared temperature. Discus need 82–88°F, swordtails need 72–79°F.

What temperature suits both discus and swordtails?

None. Discus need 82–88 °F and swordtails need 72–79 °F, so the ranges do not meet.

What size tank do discus and swordtails need together?

At least 55 gal, set by the discus. Add space for each extra fish.