Can yellow labs live with pencilfish?

Verdict
Yes, with care

Yes, with care. Yellow labs and pencilfish can share a tank, but watch one thing. Different water: yellow labs want pH 7.8–8.6, pencilfish want pH 5–7.5.

Electric yellow cichlidElectric yellow cichlid75–82°F · pH 7.8–8.6 PencilfishPencilfish75–82°F · pH 5–7.5

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–82°Electric yellow cichlid 75–82°Pencilfish 75–82°
The green band is the temperature range both can live in.
456789Electric yellow cichlid 7.8–8.6Pencilfish 5–7.5
No pH suits both. One would live in the wrong water all the time.

Size to scale

Electric yellow cichlid · 4 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

Electric yellow cichlidPencilfish
Temperature75–82 °F75–82 °F
pH7.8–8.65–7.5
Adult size4.0 in2.0 in
Minimum tank40 gal15 gal
TemperamentSemi-aggressivePeaceful
Swims atAll levelsMiddle
GroupGroups of 4+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for yellow labs

All electric yellow cichlid tank mates

Better tank mates for pencilfish

All pencilfish tank mates

Questions

Can yellow labs live with pencilfish?

Yes, with care. Yellow labs and pencilfish can share a tank, but watch one thing. Different water: yellow labs want pH 7.8–8.6, pencilfish want pH 5–7.5.

What temperature suits both yellow labs and pencilfish?

75–82 °F. Yellow labs need 75–82 °F, pencilfish need 75–82 °F.

What size tank do yellow labs and pencilfish need together?

At least 40 gal, set by the electric yellow cichlid. Add space for each extra fish.