Should I buy it?
Beckford Pencilfish
Nannostomus beckfordi
Typical trade / ID note: Nannostomus beckfordi
Also known as: golden pencilfish, beckford's pencilfish, Golden pencilfish, Beckford's pencilfish
Fishori provides conservative planning guidance, not guarantees.
Based on typical aquarium care sources; details may vary between setups. Use the numbers here as planning defaults — your room, water, and routine still shape real-world outcomes.
Peaceful, shrimp-safe mid-water schooler with a red lateral flash. Soft acidic blackwater plus six or more, and the colony settles.
Best for
Soft acidic planted tanks 60L or more alongside other nano or mid-size peaceful fish and shrimp.
Avoid if
Hard alkaline tap water, large predatory fish, or tanks under 50L.
Top things that go wrong
- Group welfare — not a solo display fish. Plan at least **6** together for normal behaviour; smaller groups often mean stress, colour loss, or nipping depending on species.
- Shrimp & snails. Shrimp: compatible in most setups. Cherry shrimp and other dwarf species coexist with peaceful small fish, though baby shrimp are food for almost any fish that gets to them.
Common mistakeBuying only four. Pencilfish school loosely but need six or more to distribute inter-fish tension and show full lateral colouring.
What most shops don't tell you
- 1.Trio purchase as nano accents. Pencilfish hide and refuse food below six; the school is the species.
- 2.Hard alkaline water community. Pencils survive but the red flash disappears and they stop spawning.
- 3.A peaceful nano schooler that pairs well with cardinal tetras and small shrimp colonies. Wants soft acidic water (pH 5.5 to 7.0, soft) for full colour. The horizontal stripe goes from pale to deep red as the school settles in a mature tank.
About this species
Beckford pencilfish are slim 4 cm characins with a horizontal stripe down the body and a red flash on the lower fins in mature males. South American blackwater origin, peaceful in nature, and one of the few mid-water tetras that tolerates a shrimp tank reliably.
- Black Neon Tetra60L min · same group, comparable tank size
- Bloodfin tetra60L min · same group, comparable tank size
- Cardinal Tetra60L min · same group, comparable tank size
- Glowlight Tetra60L min · same group, comparable tank size
- Green neon tetra60L min · same group, comparable tank size
- Lemon Tetra60L min · same group, comparable tank size
- Silver Tip Tetra60L min · same group, comparable tank size
- X-ray tetra60L min · same group, comparable tank size
- Amano Shrimpalso beginner peaceful, similar tank size
- Assassin Snailalso beginner peaceful, similar tank size
- Black Neon Tetraalso beginner peaceful, similar tank size
- Black phantom tetraalso beginner peaceful, similar tank size
- Bloodfin tetraalso beginner peaceful, similar tank size
- Blue Dream Shrimpalso beginner peaceful, similar tank size
No reverse lookups on file yet.
Plan grid
Key limits are shown above; this section adds planning detail: pH band, swim level, bioload and activity, and the radar.
Swim zones
Planning trait chart
Six indices for comparing species on paper before you spend.
- Beginner ease78
- Peacefulness90
- Community fit86
- Small-tank fit100
- Hardiness76
- Energy24
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Common setup sketches
Conservative patterns from Fishori fields — still run the pair checker for every species you add; sketches are not a stocking guarantee.
Rough 90L+ layout: one calm centrepiece, 8–12 small tetras/rasboras, 6–8 corydoras-type bottom fish — verify every name in the pair checker before buying.
Safe directions on file include: Cardinal Tetra, Rummy Nose Tetra, Corydoras Catfish.
Prioritise 6+ of Beckford Pencilfish in 60L+ with filtration sized for messy feeding — add only mates that already pass pair checks with this species.
Tank mate intelligence
Use the "Often compatible" lists as a shortlist, not a stocking plan. Always run the pair tool and check the footprint of your actual tank first. Verify behaviour for Beckford Pencilfish against your own reading before you buy.
Pair-level compatibility with this fish as anchor.
Read the blocking rule on each pair page before experimenting.
Do-not-stock combinations on conservative hobby rules.
Compare with
Run a real pair check: Beckford Pencilfish + Cardinal Tetra
Behaviour, temperament, and what to watch
Prose and lists come from the same record: read temperament first, then glass-level signals so you are not surprised after day three.
Beckford Pencilfish is peaceful in mixed company.
Stress / aggression triggers on file
- Sudden crowding
- Poor water quality
Fin nipping: Not a habitual fin-nipper, but individuals can still test fins under stress or in a crowded tank.
Predation: Not a predator toward similarly-sized community fish. The usual community caveats about mouth size still apply for very small fry or shrimp.
Territory: Not strongly territorial, but still claims a working area in the tank. Give it room to settle without overlapping the next species' patch.
Planted tanks: excellent — easy plant ideas
In the glass: typical and warning signs
- Often calm on the glass — bursts of movement around food or tank disturbance.
- Shoaling/schooling: most colour and confidence show when the group meets **6+**.
- Clamped fins, gasping at the surface, hiding non-stop, or refusing food after the first week.
- Rapid breathing when parameters swing — fix ammonia/nitrite first, then reassess mates.
- Low listed risk — still watch new introductions.
- Separate or rehome if injuries appear, one fish is pinned, or feeding becomes a daily chase.
- If water is stable but behaviour worsens, reduce stocking or remove the highest-impact species first.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Care parameters: water, food, inverts, grouping
Chemistry and group rules sit here so you are not re-reading the same line from tank mate or temperament blocks. Swim level is in the plan grid above.
Hardness
soft
Diet
omnivore
Mixed diet: a quality flake or pellet as the staple, with frozen or live foods two or three times a week.
Shrimp & snails
Shrimp: compatible in most setups. Cherry shrimp and other dwarf species coexist with peaceful small fish, though baby shrimp are food for almost any fish that gets to them.
Six or more. The colour and the calm display behaviour only come with a settled group.
Egg scatterers and schoolers still spawn in stable tanks. Have a plan for the fry, or accept that the parents and tank mates will eat them in a community setup.
- Six or more for a settled school.
- Soft acidic water (pH 5.5 to 7.0, soft) for full colour and breeding behaviour.
- Mature tank with tannins from botanicals or peat for true blackwater colour.
- 60L planted setup with a clear mid-water swim path.
- Tank volume meets or exceeds 60L published minimum for adults.
- You can stock at least 6 individuals (group welfare).
- Heater can hold 23–28°C without cooking cooler-water tank mates.
Explore and stocking hubs
Same library as the rest of Fishori: tank-mate index for this species, category peers, guides, and litre-based stocking lists where min tank on file is within the hub volume.
Plan with tools
Pair-level rules and multi-fish stocking use the same conservative engine — add this fish in the tank builder only after mates pass pair checks.
Filtration & heating
A 60L minimum tank needs a filter rated for at least 240L/hr turnover and a heater to hold 23–28°C reliably.
Plant suggestions
Beckford Pencilfish does well in planted tanks. Plants compatible with 23–28°C and pH 5.5–7:
Profile status: partially verified · Evidence tier: medium · 2 linked source(s). Fishori does not fabricate citations.
Fishori uses conservative planning rules based on these sources.
Confidence is explained in the summary at the top of this page (same tier as here), not repeated below.
How Fishori evaluates compatibility (same logic as pair and tank tools).
- Seriously Fish. Nannostomus beckfordi
Primary: species page covering blackwater origin, schooling behaviour, and the lateral-stripe display in mature males.
- Practical Fishkeeping. Beckford Pencilfish Profile
Secondary: editor write-up on tank-mate compatibility, including the shrimp-tolerant reputation.
Evidence notes
- Pencilfish hold a horizontal swim posture during the day and shift to a striped diagonal at night. The night colour pattern is normal, not stress.
- One of the few mid-water tetras that does not pursue dwarf shrimp adults. Shrimplets in a sparse tank are still at risk, but a planted shrimp colony with pencilfish typically settles.
- Fishori profiles work from typical aquarium trade sizes and hobby care norms. Specialist site checks and literature review for this species are not yet recorded here, so the ranges on this page are planning numbers rather than guarantees.