Can rummy nose tetras live with serpae tetras?

Verdict
Yes

Yes. Rummy nose tetras and serpae tetras get along in the same tank. Both are fine at 75–79°F. Plan on at least 20 gal.

Rummy nose tetraRummy nose tetra75–84°F · pH 5.5–7 Serpae tetraSerpae tetra72–79°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–79°Rummy nose tetra 75–84°Serpae tetra 72–79°
The green band is the temperature range both can live in.
456789Both: 6–7Rummy nose tetra 5.5–7Serpae tetra 6–7.5
The green band is the pH both tolerate.

Size to scale

Rummy nose tetra · 2 inSerpae tetra · 1.75 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

Rummy nose tetraSerpae tetra
Temperature75–84 °F72–79 °F
pH5.5–76–7.5
Adult size2.0 in1.75 in
Minimum tank20 gal20 gal
TemperamentPeacefulSemi-aggressive
Swims atMiddleMiddle
GroupGroups of 6+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for rummy nose tetras

All rummy nose tetra tank mates

Better tank mates for serpae tetras

All serpae tetra tank mates

Questions

Can rummy nose tetras live with serpae tetras?

Yes. Rummy nose tetras and serpae tetras get along in the same tank. Both are fine at 75–79°F. Plan on at least 20 gal.

What temperature suits both rummy nose tetras and serpae tetras?

75–79 °F. Rummy nose tetras need 75–84 °F, serpae tetras need 72–79 °F.

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

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