Can hillstream loaches live with cardinal tetras?

Verdict
No

No. Hillstream loaches and cardinal tetras should not share a tank. No shared temperature. Hillstream loaches need 68–75°F, cardinal tetras need 76–84°F.

Hillstream loachHillstream loach68–75°F · pH 6.5–7.5 Cardinal tetraCardinal tetra76–84°F · pH 4.6–7

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Hillstream loach 68–75°Cardinal tetra 76–84°
The ranges do not meet, so one of them would always be too warm or too cold.
456789Both: 6.5–7Hillstream loach 6.5–7.5Cardinal tetra 4.6–7
The green band is the pH both tolerate.

Size to scale

Hillstream loach · 2.5 inCardinal 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

Hillstream loachCardinal tetra
Temperature68–75 °F76–84 °F
pH6.5–7.54.6–7
Adult size2.5 in2.0 in
Minimum tank20 gal20 gal
TemperamentPeacefulPeaceful
Swims atBottomMiddle
GroupGroups of 3+Groups of 6+
DietHerbivoreOmnivore

Better tank mates for hillstream loaches

All hillstream loach tank mates

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Questions

Can hillstream loaches live with cardinal tetras?

No. Hillstream loaches and cardinal tetras should not share a tank. No shared temperature. Hillstream loaches need 68–75°F, cardinal tetras need 76–84°F.

What temperature suits both hillstream loaches and cardinal tetras?

None. Hillstream loaches need 68–75 °F and cardinal tetras need 76–84 °F, so the ranges do not meet.

What size tank do hillstream loaches and cardinal tetras need together?

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