Can pencilfish live with clown plecos?

Verdict
Yes

Yes. Pencilfish and clown plecos make a good pair. Both are fine at 75–82°F. Plan on at least 20 gal.

PencilfishPencilfish75–82°F · pH 5–7.5 Clown plecoClown pleco73–82°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°Clown pleco 73–82°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Pencilfish 5–7.5Clown pleco 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Pencilfish · 2 inClown pleco · 3.5 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

PencilfishClown pleco
Temperature75–82 °F73–82 °F
pH5–7.56.5–7.5
Adult size2.0 in3.5 in
Minimum tank15 gal20 gal
TemperamentPeacefulPeaceful
Swims atMiddleBottom
GroupGroups of 6+Alone or in pairs
DietOmnivoreHerbivore

Better tank mates for pencilfish

All pencilfish tank mates

Better tank mates for clown plecos

All clown pleco tank mates

Questions

Can pencilfish live with clown plecos?

Yes. Pencilfish and clown plecos make a good pair. Both are fine at 75–82°F. Plan on at least 20 gal.

What temperature suits both pencilfish and clown plecos?

75–82 °F. Pencilfish need 75–82 °F, clown plecos need 73–82 °F.

What size tank do pencilfish and clown plecos need together?

At least 20 gal, set by the clown pleco. Add space for each extra fish.