Can bettas live with rummy nose tetras?

Verdict
Yes

Yes, bettas and rummy nose tetras can live together. Both are fine at 76–82°F. Plan on at least 20 gal.

BettaBetta76–82°F · pH 6.5–7.5 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: 76–82°Betta 76–82°Rummy nose tetra 75–84°
The green band is the temperature range both can live in.
456789Both: 6.5–7Betta 6.5–7.5Rummy nose tetra 5.5–7
The green band is the pH both tolerate.

Size to scale

Betta · 2.5 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

BettaRummy nose tetra
Temperature76–82 °F75–84 °F
pH6.5–7.55.5–7
Adult size2.5 in2.0 in
Minimum tank5 gal20 gal
TemperamentSemi-aggressivePeaceful
Swims atTopMiddle
GroupOne per tankGroups of 6+
DietCarnivoreOmnivore

Better tank mates for bettas

All betta tank mates

Better tank mates for rummy nose tetras

All rummy nose tetra tank mates

Questions

Can bettas live with rummy nose tetras?

Yes, bettas and rummy nose tetras can live together. Both are fine at 76–82°F. Plan on at least 20 gal.

What temperature suits both bettas and rummy nose tetras?

76–82 °F. Bettas need 76–82 °F, rummy nose tetras need 75–84 °F.

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

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