Can otocinclus live with rosy barbs?

Verdict
Yes

Yes, otocinclus and rosy barbs can live together. Both are fine at 72–77°F. Plan on at least 30 gal.

OtocinclusOtocinclus72–79°F · pH 6–7.5 Rosy barbRosy barb64–77°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–77°Otocinclus 72–79°Rosy barb 64–77°
The green band is the temperature range both can live in.
456789Both: 6–7.5Otocinclus 6–7.5Rosy barb 6–7.5
The green band is the pH both tolerate.

Size to scale

Otocinclus · 2 inRosy barb · 4 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

OtocinclusRosy barb
Temperature72–79 °F64–77 °F
pH6–7.56–7.5
Adult size2.0 in4.0 in
Minimum tank20 gal30 gal
TemperamentPeacefulSemi-aggressive
Swims atBottomMiddle
GroupGroups of 6+Groups of 6+
DietHerbivoreOmnivore

Better tank mates for otocinclus

All otocinclus tank mates

Better tank mates for rosy barbs

All rosy barb tank mates

Questions

Can otocinclus live with rosy barbs?

Yes, otocinclus and rosy barbs can live together. Both are fine at 72–77°F. Plan on at least 30 gal.

What temperature suits both otocinclus and rosy barbs?

72–77 °F. Otocinclus need 72–79 °F, rosy barbs need 64–77 °F.

What size tank do otocinclus and rosy barbs need together?

At least 30 gal, set by the rosy barb. Add space for each extra fish.