Three-lined Pencilfish
Nannostomus sp.
Three-lined Pencilfish (Nannostomus sp.) — Varies care, Peaceful, under Other. Minimum tank in the app: 14.5 US gal min; aim for 72–82°F and pH 6.5–7.5. The Three-lined Pencilfish is ideal for hobbyists seeking a small, intriguing species that thrives in well-planned environments.

Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
South America
- South America
Regional colours match the stocking calculator’s origin map.
Three-lined Pencilfish Tank Setup
Create a balanced environment with plenty of cover using plants and driftwood, while ensuring open swimming spaces in the mid-zone. Optimal flow should be moderate, and substrate can range from fine to sandy, allowing for comfortable movement. Lighting should be subdued to mimic natural habitats, promoting a sense of security for the fish.
What Do Three-lined Pencilfishs Eat?
The Three-lined Pencilfish has a moderate feeding speed and can be outcompeted for food if not provided with adequate quantity. A varied diet rich in high-quality flakes, pellets, and occasional live or frozen treats will enhance their health and coloration, but overfeeding should be avoided to prevent water quality issues.
Three-lined Pencilfish Tank Mates
Ideal tank mates include similarly sized and temperamentally compatible species such as small tetras and rasboras. Larger or overly assertive fish may provoke stress, while intraspecies interactions are generally harmonious provided there is ample space and hiding spots to diffuse potential competition.
Are Three-lined Pencilfishs Good for Beginners?
Care demand varies with setup and individual fish; use the numbers above as your baseline. Aquarists often underestimate the need for structured environments, leading to timid behaviour and poor health. neglecting to monitor compatibility with more aggressive species can result in stress or aggression, undermining the fish's wellbeing.
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