Can otocinclus live with rummy nose tetras?

Verdict
Yes

Yes. Otocinclus and rummy nose tetras make a good pair. Both are fine at 75–79°F. Plan on at least 20 gal.

OtocinclusOtocinclus72–79°F · pH 6–7.5 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: 75–79°Otocinclus 72–79°Rummy nose tetra 75–84°
The green band is the temperature range both can live in.
456789Both: 6–7Otocinclus 6–7.5Rummy nose tetra 5.5–7
The green band is the pH both tolerate.

Size to scale

Otocinclus · 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

OtocinclusRummy nose tetra
Temperature72–79 °F75–84 °F
pH6–7.55.5–7
Adult size2.0 in2.0 in
Minimum tank20 gal20 gal
TemperamentPeacefulPeaceful
Swims atBottomMiddle
GroupGroups of 6+Groups of 6+
DietHerbivoreOmnivore

Better tank mates for otocinclus

All otocinclus tank mates

Better tank mates for rummy nose tetras

All rummy nose tetra tank mates

Questions

Can otocinclus live with rummy nose tetras?

Yes. Otocinclus and rummy nose tetras make a good pair. Both are fine at 75–79°F. Plan on at least 20 gal.

What temperature suits both otocinclus and rummy nose tetras?

75–79 °F. Otocinclus need 72–79 °F, rummy nose tetras need 75–84 °F.

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

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