Can bettas live with black neon tetras?

Verdict
Yes

Yes. Bettas and black neon tetras get along in the same tank. Both are fine at 76–81°F. Plan on at least 15 gal.

BettaBetta76–82°F · pH 6.5–7.5 Black neon tetraBlack neon tetra73–81°F · pH 5.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–81°Betta 76–82°Black neon tetra 73–81°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Betta 6.5–7.5Black neon tetra 5.5–7.5
The green band is the pH both tolerate.

Size to scale

Betta · 2.5 inBlack neon tetra · 1.5 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

BettaBlack neon tetra
Temperature76–82 °F73–81 °F
pH6.5–7.55.5–7.5
Adult size2.5 in1.5 in
Minimum tank5 gal15 gal
TemperamentSemi-aggressivePeaceful
Swims atTopMiddle
GroupOne per tankGroups of 6+
DietCarnivoreOmnivore

Better tank mates for bettas

All betta tank mates

Better tank mates for black neon tetras

All black neon tetra tank mates

Questions

Can bettas live with black neon tetras?

Yes. Bettas and black neon tetras get along in the same tank. Both are fine at 76–81°F. Plan on at least 15 gal.

What temperature suits both bettas and black neon tetras?

76–81 °F. Bettas need 76–82 °F, black neon tetras need 73–81 °F.

What size tank do bettas and black neon tetras need together?

At least 15 gal, set by the black neon tetra. Add space for each extra fish.