Can guppies live with red tail sharks?

Verdict
Yes

Yes. Guppies and red tail sharks make a good pair. Both are fine at 72–79°F. Plan on at least 55 gal.

GuppyGuppy72–82°F · pH 6.8–7.8 Red tail sharkRed tail shark72–79°F · pH 6.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–79°Guppy 72–82°Red tail shark 72–79°
The green band is the temperature range both can live in.
456789Both: 6.8–7.5Guppy 6.8–7.8Red tail shark 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Guppy · 2 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

GuppyRed tail shark
Temperature72–82 °F72–79 °F
pH6.8–7.86.5–7.5
Adult size2.0 in5.0 in
Minimum tank10 gal55 gal
TemperamentPeacefulSemi-aggressive
Swims atTopBottom
GroupGroups of 3+One per tank
DietOmnivoreOmnivore

Better tank mates for guppies

All guppy tank mates

Better tank mates for red tail sharks

All red tail shark tank mates

Questions

Can guppies live with red tail sharks?

Yes. Guppies and red tail sharks make a good pair. Both are fine at 72–79°F. Plan on at least 55 gal.

What temperature suits both guppies and red tail sharks?

72–79 °F. Guppies need 72–82 °F, red tail sharks need 72–79 °F.

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

At least 55 gal, set by the red tail shark. Add space for each extra fish.