Can hillstream loaches live with fancy goldfish?

Verdict
Yes

Yes. Hillstream loaches and fancy goldfish make a good pair. Both are fine at 68–74°F. Plan on at least 30 gal.

Hillstream loachHillstream loach68–75°F · pH 6.5–7.5 Fancy goldfishFancy goldfish65–74°F · pH 7–8

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 68–74°Hillstream loach 68–75°Fancy goldfish 65–74°
The green band is the temperature range both can live in.
456789Both: 7–7.5Hillstream loach 6.5–7.5Fancy goldfish 7–8
The green band is the pH both tolerate.

Size to scale

Hillstream loach · 2.5 inFancy goldfish · 6 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 loachFancy goldfish
Temperature68–75 °F65–74 °F
pH6.5–7.57–8
Adult size2.5 in6.0 in
Minimum tank20 gal30 gal
TemperamentPeacefulPeaceful
Swims atBottomAll levels
GroupGroups of 3+Alone or in pairs
DietHerbivoreOmnivore

Better tank mates for hillstream loaches

All hillstream loach tank mates

Better tank mates for fancy goldfish

All fancy goldfish tank mates

Questions

Can hillstream loaches live with fancy goldfish?

Yes. Hillstream loaches and fancy goldfish make a good pair. Both are fine at 68–74°F. Plan on at least 30 gal.

What temperature suits both hillstream loaches and fancy goldfish?

68–74 °F. Hillstream loaches need 68–75 °F, fancy goldfish need 65–74 °F.

What size tank do hillstream loaches and fancy goldfish need together?

At least 30 gal, set by the fancy goldfish. Add space for each extra fish.