Can pencilfish live with electric blue acaras?

Verdict
Yes

Yes. Pencilfish and electric blue acaras make a good pair. Both are fine at 75–82°F. Plan on at least 30 gal.

PencilfishPencilfish75–82°F · pH 5–7.5 Electric blue acaraElectric blue acara72–82°F · pH 6.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–82°Pencilfish 75–82°Electric blue acara 72–82°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Pencilfish 5–7.5Electric blue acara 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Pencilfish · 2 inElectric blue acara · 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

PencilfishElectric blue acara
Temperature75–82 °F72–82 °F
pH5–7.56.5–7.5
Adult size2.0 in6.0 in
Minimum tank15 gal30 gal
TemperamentPeacefulSemi-aggressive
Swims atMiddleMiddle
GroupGroups of 6+Alone or in pairs
DietOmnivoreOmnivore

Better tank mates for pencilfish

All pencilfish tank mates

Better tank mates for electric blue acaras

All electric blue acara tank mates

Questions

Can pencilfish live with electric blue acaras?

Yes. Pencilfish and electric blue acaras make a good pair. Both are fine at 75–82°F. Plan on at least 30 gal.

What temperature suits both pencilfish and electric blue acaras?

75–82 °F. Pencilfish need 75–82 °F, electric blue acaras need 72–82 °F.

What size tank do pencilfish and electric blue acaras need together?

At least 30 gal, set by the electric blue acara. Add space for each extra fish.