Can hillstream loaches live with upside down catfish?

Verdict
Yes

Yes. Hillstream loaches and upside down catfish make a good pair. Both are fine at 72–75°F. Plan on at least 30 gal.

Hillstream loachHillstream loach68–75°F · pH 6.5–7.5 Upside down catfishUpside down catfish72–79°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–75°Hillstream loach 68–75°Upside down catfish 72–79°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Hillstream loach 6.5–7.5Upside down catfish 6–7.5
The green band is the pH both tolerate.

Size to scale

Hillstream loach · 2.5 inUpside down catfish · 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

Hillstream loachUpside down catfish
Temperature68–75 °F72–79 °F
pH6.5–7.56–7.5
Adult size2.5 in4.0 in
Minimum tank20 gal30 gal
TemperamentPeacefulPeaceful
Swims atBottomBottom
GroupGroups of 3+Groups of 3+
DietHerbivoreOmnivore

Better tank mates for hillstream loaches

All hillstream loach tank mates

Better tank mates for upside down catfish

All upside down catfish tank mates

Questions

Can hillstream loaches live with upside down catfish?

Yes. Hillstream loaches and upside down catfish make a good pair. Both are fine at 72–75°F. Plan on at least 30 gal.

What temperature suits both hillstream loaches and upside down catfish?

72–75 °F. Hillstream loaches need 68–75 °F, upside down catfish need 72–79 °F.

What size tank do hillstream loaches and upside down catfish need together?

At least 30 gal, set by the upside down catfish. Add space for each extra fish.