Can upside down catfish live with dwarf neon rainbowfish?

Verdict
Yes

Yes. Upside down catfish and dwarf neon rainbowfish make a good pair. Both are fine at 75–79°F. Plan on at least 30 gal.

Upside down catfishUpside down catfish72–79°F · pH 6–7.5 Dwarf neon rainbowfishDwarf neon rainbowfish75–82°F · pH 6.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–79°Upside down catfish 72–79°Dwarf neon rainbowfish 75–82°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Upside down catfish 6–7.5Dwarf neon rainbowfish 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Upside down catfish · 4 inDwarf neon rainbowfish · 2.5 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

Upside down catfishDwarf neon rainbowfish
Temperature72–79 °F75–82 °F
pH6–7.56.5–7.5
Adult size4.0 in2.5 in
Minimum tank30 gal20 gal
TemperamentPeacefulPeaceful
Swims atBottomMiddle
GroupGroups of 3+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for upside down catfish

All upside down catfish tank mates

Better tank mates for dwarf neon rainbowfish

All dwarf neon rainbowfish tank mates

Questions

Can upside down catfish live with dwarf neon rainbowfish?

Yes. Upside down catfish and dwarf neon rainbowfish make a good pair. Both are fine at 75–79°F. Plan on at least 30 gal.

What temperature suits both upside down catfish and dwarf neon rainbowfish?

75–79 °F. Upside down catfish need 72–79 °F, dwarf neon rainbowfish need 75–82 °F.

What size tank do upside down catfish and dwarf neon rainbowfish need together?

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