Can assassin snails live with pencilfish?

Verdict
Yes

Yes. Assassin snails and pencilfish make a good pair. Both are fine at 75–80°F. Plan on at least 15 gal.

Assassin snailAssassin snail75–80°F · pH 7–8 PencilfishPencilfish75–82°F · pH 5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–80°Assassin snail 75–80°Pencilfish 75–82°
The green band is the temperature range both can live in.
456789Both: 7–7.5Assassin snail 7–8Pencilfish 5–7.5
The green band is the pH both tolerate.

Size to scale

Assassin snail · 1 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

Assassin snailPencilfish
Temperature75–80 °F75–82 °F
pH7–85–7.5
Adult size1.0 in2.0 in
Minimum tank5 gal15 gal
TemperamentPeacefulPeaceful
Swims atBottomMiddle
GroupAlone or in pairsGroups of 6+
DietCarnivoreOmnivore

Better tank mates for assassin snails

All assassin snail tank mates

Better tank mates for pencilfish

All pencilfish tank mates

Questions

Can assassin snails live with pencilfish?

Yes. Assassin snails and pencilfish make a good pair. Both are fine at 75–80°F. Plan on at least 15 gal.

What temperature suits both assassin snails and pencilfish?

75–80 °F. Assassin snails need 75–80 °F, pencilfish need 75–82 °F.

What size tank do assassin snails and pencilfish need together?

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