Can guppies live with upside down catfish?

Verdict
Yes

Yes, guppies and upside down catfish can live together. Both are fine at 72–79°F. Plan on at least 30 gal.

GuppyGuppy72–82°F · pH 6.8–7.8 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: 72–79°Guppy 72–82°Upside down catfish 72–79°
The green band is the temperature range both can live in.
456789Both: 6.8–7.5Guppy 6.8–7.8Upside down catfish 6–7.5
The green band is the pH both tolerate.

Size to scale

Guppy · 2 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

GuppyUpside down catfish
Temperature72–82 °F72–79 °F
pH6.8–7.86–7.5
Adult size2.0 in4.0 in
Minimum tank10 gal30 gal
TemperamentPeacefulPeaceful
Swims atTopBottom
GroupGroups of 3+Groups of 3+
DietOmnivoreOmnivore

Better tank mates for guppies

All guppy tank mates

Better tank mates for upside down catfish

All upside down catfish tank mates

Questions

Can guppies live with upside down catfish?

Yes, guppies and upside down catfish can live together. Both are fine at 72–79°F. Plan on at least 30 gal.

What temperature suits both guppies and upside down catfish?

72–79 °F. Guppies need 72–82 °F, upside down catfish need 72–79 °F.

What size tank do guppies and upside down catfish need together?

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