Can fancy goldfish live with glass catfish?

Verdict
No

No. Fancy goldfish and glass catfish should not share a tank. Fancy goldfish are coldwater animals (65–74°F); glass catfish need 75–80°F. No temperature suits both.

Fancy goldfishFancy goldfish65–74°F · pH 7–8 Glass catfishGlass catfish75–80°F · pH 6.5–7.5

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Fancy goldfish 65–74°Glass catfish 75–80°
The ranges do not meet, so one of them would always be too warm or too cold.
456789Both: 7–7.5Fancy goldfish 7–8Glass catfish 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Fancy goldfish · 6 inGlass catfish · 3 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

Fancy goldfishGlass catfish
Temperature65–74 °F75–80 °F
pH7–86.5–7.5
Adult size6.0 in3.0 in
Minimum tank30 gal30 gal
TemperamentPeacefulPeaceful
Swims atAll levelsMiddle
GroupAlone or in pairsGroups of 6+
DietOmnivoreCarnivore

Better tank mates for fancy goldfish

All fancy goldfish tank mates

Better tank mates for glass catfish

All glass catfish tank mates

Questions

Can fancy goldfish live with glass catfish?

No. Fancy goldfish and glass catfish should not share a tank. Fancy goldfish are coldwater animals (65–74°F); glass catfish need 75–80°F. No temperature suits both.

What temperature suits both fancy goldfish and glass catfish?

None. Fancy goldfish need 65–74 °F and glass catfish need 75–80 °F, so the ranges do not meet.

What size tank do fancy goldfish and glass catfish need together?

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