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Marilyn's Pencilfish

Nannostomus marilynae

Freshwater South America

A delicate, slender blackwater pencilfish that swims with a gentle oblique posture near the surface. It requires soft, acidic conditions and quiet, shaded quarters to feel secure. Keep in generous shoals alongside gentle tankmates to avoid aggressive competition during feeding time.

Also called: Greenstripe pencilfish, Marilyn's pencilfish.

3.5 cm adult length, drawn to scale. slim body.

Try it in the planner Opens a tank sized to its minimum with 8 fish added.

What it needs

ItemValueBecause
Adult length 3.5 cm Used for the Space check: the tank must be long enough for the fish to turn round.
Smallest tank 45 L, at least 45 cm long estimated The least water and floor length this species is kept in for good, as a single fish or smallest group.
Extra water per added fish 3 L estimated What each further fish adds once the minimum is met.
Waste load Class 1 of 5 estimated How much waste an adult makes against its size. Feeds the Load check.
Temperature 23 to 28 C Stock sharing a tank need overlapping ranges.
pH 4.5 to 6.8 Compared with tankmates in the Water check.
Hardness GH 1 to 5, KH 0 to 3 Degrees of general and carbonate hardness.
Flow Low Low-flow fish are stressed in a strong current.
Light Dim Matched to the lighting class on the needs sheet.
Group size At least 8, ideally 12 Kept alone or in small numbers it hides, fades or turns on tankmates.
Temperament Peaceful Territorial: weak.
Swims in Upper water Fish that use different levels share a tank more easily.
Lifespan About 3 years A fish is a long commitment.
Experience Some experience helps A guide to how forgiving the species is of mistakes.
Jumps Yes Keep the tank covered.

Tags marked estimated are judged from the size and habits of the species rather than measured, so treat them as a sensible default.

Diet and tank layout

Marilyn's Pencilfish is an micro feeder that swims in the upper water. It is safe with plants. Give it plenty of cover.

Tankmates

Works with

No close matches in the data. Check the pair tool.

Depends

Avoid

Compare any two fish on the compatibility page, or print the equipment for a stock on the needs sheet. How this is worked out: the method.