Can guppies live with rummy nose tetras?

Verdict
Yes

Yes. Guppies and rummy nose tetras make a good pair. Both are fine at 75–82°F. Plan on at least 20 gal.

GuppyGuppy72–82°F · pH 6.8–7.8 Rummy nose tetraRummy nose tetra75–84°F · pH 5.5–7

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–82°Guppy 72–82°Rummy nose tetra 75–84°
The green band is the temperature range both can live in.
456789Both: 6.8–7Guppy 6.8–7.8Rummy nose tetra 5.5–7
The green band is the pH both tolerate.

Size to scale

Guppy · 2 inRummy nose tetra · 2 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

GuppyRummy nose tetra
Temperature72–82 °F75–84 °F
pH6.8–7.85.5–7
Adult size2.0 in2.0 in
Minimum tank10 gal20 gal
TemperamentPeacefulPeaceful
Swims atTopMiddle
GroupGroups of 3+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for guppies

All guppy tank mates

Better tank mates for rummy nose tetras

All rummy nose tetra tank mates

Questions

Can guppies live with rummy nose tetras?

Yes. Guppies and rummy nose tetras make a good pair. Both are fine at 75–82°F. Plan on at least 20 gal.

What temperature suits both guppies and rummy nose tetras?

75–82 °F. Guppies need 72–82 °F, rummy nose tetras need 75–84 °F.

What size tank do guppies and rummy nose tetras need together?

At least 20 gal, set by the rummy nose tetra. Add space for each extra fish.