Can otocinclus live with hatchetfish?

Verdict
Yes

Yes, otocinclus and hatchetfish can live together. Both are fine at 75–79°F. Plan on at least 20 gal.

OtocinclusOtocinclus72–79°F · pH 6–7.5 HatchetfishHatchetfish75–81°F · pH 5.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–79°Otocinclus 72–79°Hatchetfish 75–81°
The green band is the temperature range both can live in.
456789Both: 6–7.5Otocinclus 6–7.5Hatchetfish 5.5–7.5
The green band is the pH both tolerate.

Size to scale

Otocinclus · 2 inHatchetfish · 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

OtocinclusHatchetfish
Temperature72–79 °F75–81 °F
pH6–7.55.5–7.5
Adult size2.0 in1.5 in
Minimum tank20 gal20 gal
TemperamentPeacefulPeaceful
Swims atBottomTop
GroupGroups of 6+Groups of 6+
DietHerbivoreCarnivore

Better tank mates for otocinclus

All otocinclus tank mates

Better tank mates for hatchetfish

All hatchetfish tank mates

Questions

Can otocinclus live with hatchetfish?

Yes, otocinclus and hatchetfish can live together. Both are fine at 75–79°F. Plan on at least 20 gal.

What temperature suits both otocinclus and hatchetfish?

75–79 °F. Otocinclus need 72–79 °F, hatchetfish need 75–81 °F.

What size tank do otocinclus and hatchetfish need together?

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