Can otocinclus live with black neon tetras?

Verdict
Yes

Yes. Otocinclus and black neon tetras get along in the same tank. Both are fine at 73–79°F. Plan on at least 20 gal.

OtocinclusOtocinclus72–79°F · pH 6–7.5 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: 73–79°Otocinclus 72–79°Black neon tetra 73–81°
The green band is the temperature range both can live in.
456789Both: 6–7.5Otocinclus 6–7.5Black neon tetra 5.5–7.5
The green band is the pH both tolerate.

Size to scale

Otocinclus · 2 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

OtocinclusBlack neon tetra
Temperature72–79 °F73–81 °F
pH6–7.55.5–7.5
Adult size2.0 in1.5 in
Minimum tank20 gal15 gal
TemperamentPeacefulPeaceful
Swims atBottomMiddle
GroupGroups of 6+Groups of 6+
DietHerbivoreOmnivore

Better tank mates for otocinclus

All otocinclus tank mates

Better tank mates for black neon tetras

All black neon tetra tank mates

Questions

Can otocinclus live with black neon tetras?

Yes. Otocinclus and black neon tetras get along in the same tank. Both are fine at 73–79°F. Plan on at least 20 gal.

What temperature suits both otocinclus and black neon tetras?

73–79 °F. Otocinclus need 72–79 °F, black neon tetras need 73–81 °F.

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

At least 20 gal, set by the otocinclus. Add space for each extra fish.