Can ember tetras live with pencilfish?

Verdict
Yes

Yes. Ember tetras and pencilfish make a good pair. Both are fine at 75–82°F. Plan on at least 15 gal.

Ember tetraEmber tetra73–84°F · pH 5.5–7 PencilfishPencilfish75–82°F · pH 5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–82°Ember tetra 73–84°Pencilfish 75–82°
The green band is the temperature range both can live in.
456789Both: 5.5–7Ember tetra 5.5–7Pencilfish 5–7.5
The green band is the pH both tolerate.

Size to scale

Ember tetra · 0.8 inPencilfish · 2 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

Ember tetraPencilfish
Temperature73–84 °F75–82 °F
pH5.5–75–7.5
Adult size0.8 in2.0 in
Minimum tank5 gal15 gal
TemperamentPeacefulPeaceful
Swims atMiddleMiddle
GroupGroups of 6+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for ember tetras

All ember tetra tank mates

Better tank mates for pencilfish

All pencilfish tank mates

Questions

Can ember tetras live with pencilfish?

Yes. Ember tetras and pencilfish make a good pair. Both are fine at 75–82°F. Plan on at least 15 gal.

What temperature suits both ember tetras and pencilfish?

75–82 °F. Ember tetras need 73–84 °F, pencilfish need 75–82 °F.

What size tank do ember tetras and pencilfish need together?

At least 15 gal, set by the pencilfish. Add space for each extra fish.