Can discus live with red tail sharks?

Verdict
No

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

DiscusDiscus82–88°F · pH 5.5–7 Red tail sharkRed tail shark72–79°F · pH 6.5–7.5

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Discus 82–88°Red tail shark 72–79°
The ranges do not meet, so one of them would always be too warm or too cold.
456789Both: 6.5–7Discus 5.5–7Red tail shark 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Discus · 6 inRed tail shark · 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

DiscusRed tail shark
Temperature82–88 °F72–79 °F
pH5.5–76.5–7.5
Adult size6.0 in5.0 in
Minimum tank55 gal55 gal
TemperamentPeacefulSemi-aggressive
Swims atMiddleBottom
GroupGroups of 5+One per tank
DietCarnivoreOmnivore

Better tank mates for discus

All discus tank mates

Better tank mates for red tail sharks

All red tail shark tank mates

Questions

Can discus live with red tail sharks?

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

What temperature suits both discus and red tail sharks?

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

What size tank do discus and red tail sharks need together?

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