Can apistogramma live with upside down catfish?

Verdict
Yes

Yes. Apistogramma and upside down catfish make a good pair. Both are fine at 75–79°F. Plan on at least 30 gal.

ApistogrammaApistogramma75–84°F · pH 5–7 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: 75–79°Apistogramma 75–84°Upside down catfish 72–79°
The green band is the temperature range both can live in.
456789Both: 6–7Apistogramma 5–7Upside down catfish 6–7.5
The green band is the pH both tolerate.

Size to scale

Apistogramma · 3 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

ApistogrammaUpside down catfish
Temperature75–84 °F72–79 °F
pH5–76–7.5
Adult size3.0 in4.0 in
Minimum tank20 gal30 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomBottom
GroupAlone or in pairsGroups of 3+
DietCarnivoreOmnivore

Better tank mates for apistogramma

All apistogramma tank mates

Better tank mates for upside down catfish

All upside down catfish tank mates

Questions

Can apistogramma live with upside down catfish?

Yes. Apistogramma and upside down catfish make a good pair. Both are fine at 75–79°F. Plan on at least 30 gal.

What temperature suits both apistogramma and upside down catfish?

75–79 °F. Apistogramma need 75–84 °F, upside down catfish need 72–79 °F.

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

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