Harrison's Pencilfish tank mates
Nannostomus harrisoni
5 rated pairings from the Harrison's Pencilfish care guide. Compatibility here means water, temperament, tank zone and adult size all line up — the note on each card says why. Harrison's Pencilfish needs at least 10 gallons on its own; every companion adds to that.
Excellent matches
5 · Same water, complementary zones, no conflict.
Neon Tetra
Paracheirodon innesi
10 gal min · 1.5" adult · Peaceful
Similar size and peaceful temperament; both prefer soft, acidic water
Cardinal Tetra
Paracheirodon axelrodi
15 gal min · 2" adult · Peaceful
Comparable water requirements and non-aggressive behavior
Otocinclus
Otocinclus vittatus
10 gal min · 1.5" adult · Peaceful
Small, peaceful bottom dweller that won't compete for food
Amano Shrimp
Caridina multidentata
10 gal min · 2" adult · Peaceful
Peaceful invertebrate that helps with algae control and won't harm pencilfish
Java Fern
Microsorum pteropus
Provides essential shelter and shade that pencilfish require
Planning this tank?
Run the whole stock list through the calculator — it checks bioload and schooling numbers, not just pairings.