Dwarf pencilfish care
Nannostomus marginatus · Northern South America: Brazil, Guyana, Suriname, Colombia and Peru
Dwarf pencilfish are among the smallest pencilfish, under an inch and a half, striped gold, black and red.
- Tank size
- 10 US gal or larger
- Temperature
- 75 to 82 °F (24 to 28 °C)
- Group size
- 6 or more
- Temperament
- Peaceful
- Adult size
- 1.4 in
- pH
- 5.5 to 7.5
- Hardness (GH)
- 1 to 10 dGH
- Lifespan
- 3 to 5 years
- Diet
- Micropredator
- Care level
- Moderate
In a 10 gallon
20¼ × 10½ × 12 9/16 in outsideHow to keep dwarf pencilfish
Dwarf pencilfish are among the smallest pencilfish, under an inch and a half, striped gold, black and red. Keep six or more in a planted 10 gallon or larger tank with soft, slightly acidic water and a tight lid; they are timid, slow feeders, so give them calm, small tankmates.
Diet: Micropredator: baby brine shrimp, daphnia, crushed flakes, micro pellets. Fish food types compared · how often to feed.
Where they swim: Middle of the tank.
Dwarf pencilfish tank mates
Share the temperature and water, and neither side eats, nips or bullies the other. Check the full group in the stocking checker.
Clown killifish
1.4 in · 5+ gal · 72–80 °F
Marbled hatchetfish
1.5 in · 20+ gal · 75–82 °F
Medaka
1.5 in · 10+ gal · 65–82 °F
African dwarf frog
1.5 in · 10+ gal · 75–82 °F
Umbrella dwarf cichlid
1.5 in · 15+ gal · 70–79 °F
Cherry shrimp
1.6 in · 5+ gal · 65–82 °F
Sparkling gourami
1.6 in · 10+ gal · 76–82 °F
Pitbull pleco
1.6 in · 20+ gal · 72–79 °F
Keep apart
White cloud mountain minnow: No shared temperature: dwarf pencilfish need 75 to 82 °F, white cloud mountain minnows 64 to 72 °F.
Pea puffer: Pea puffers belong in a tank of their own.
Fancy goldfish: Adult fancy goldfish eat fish under about 2 in; dwarf pencilfish grow to 1.4 in.
Golden wonder killifish: Adult golden wonder killifish eat fish under about 2 in; dwarf pencilfish grow to 1.4 in.
Red-tail dwarf puffer: Red-tail dwarf puffers belong in a tank of their own.
Everglades pygmy sunfish: Everglades pygmy sunfish belong in a tank of their own.
What a dwarf pencilfish tank needs
A tank of 10 US gallons or more (such as the 10 gallon) with a tight lid (they jump), and the equipment below.
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Aquarium Co-Op Easy Flow Sponge Filter, Small
A sponge filter gives gentle flow and cannot pull in small fish. It runs from an air pump, with airline tubing and a check valve, all sold separately.
hygger AquaFall Aquarium Filter, S
Rated by the maker for 7–10 US gal, which covers a 10 gallon dwarf pencilfish tank without being built for a far bigger one.
Aqueon QuietFlow Internal Power Filter 5–15 gal
Rated by the maker for 5–15 US gal, which covers a 10 gallon dwarf pencilfish tank without being built for a far bigger one.
hygger Precise Aquarium Heater 50W
Dwarf pencilfish need 75 to 82 °F; most homes run cooler, so a heater holds the temperature.
API Freshwater Master Test Kit
Tests ammonia, nitrite, nitrate and pH, the readings that matter most before and after adding dwarf pencilfish.
Seachem Prime 100 mL
Removes chlorine and chloramine from tap water at every water change.
Fluval Edge Thermometer
Shows the water temperature at a glance, so you know it stays within 75 to 82 °F.
More choices, each with the reason it is in or out: Filters for a 10 gallon tank · Heaters for a 10 gallon tank. We don’t list fish food: any good brand of the foods under Diet will do. Plan the whole tank's equipment →
Common dwarf pencilfish problems
- Fast eaters take all the food; feed where they gather, or keep only calm tankmates.
- They jump; use a lid.
Test the water first whenever fish look unwell: see what your readings mean, then match the symptom. For disease, a vet who treats fish can diagnose it and advise treatment.
More to compare
Sources
Name, origin and adult size checked against Wikipedia: Nannostomus marginatus. Temperature, pH, hardness, group size, lifespan and minimum tank size are common hobby guidance, not figures from that article. Ranges are the range the species tolerates; aim for the middle. Minimum tank sizes are for an adult group. Drawings are our own; photo credits follow.
Photo credits
Real photographs from Wikimedia Commons, resized and cropped to fit; each is used under the license named.
- Dwarf pencilfish Fanch from Paris, France, CC BY 2.0, via Wikimedia Commons
- Clown killifish Dornenwolf, CC BY 2.0, via Wikimedia Commons
- Marbled hatchetfish Sven Kullander, CC BY-SA 4.0, via Wikimedia Commons
- Medaka Seotaro, CC BY-SA 3.0, via Wikimedia Commons
- African dwarf frog Stuart Halliday, CC BY 3.0, via Wikimedia Commons
- Umbrella dwarf cichlid Gordon Axmann, CC BY-SA 3.0, via Wikimedia Commons
- Cherry shrimp TheJammingYam, CC BY-SA 3.0, via Wikimedia Commons
- Sparkling gourami BEDO (Thailand), CC BY-SA 4.0, via Wikimedia Commons
- Pitbull pleco Haplochromis, CC BY-SA 3.0, via Wikimedia Commons
- White cloud mountain minnow Petrtyl, CC BY 4.0, via Wikimedia Commons
- Pea puffer Beta Mahatvaraj, CC BY-SA 4.0, via Wikimedia Commons
- Fancy goldfish Benson Kua, CC BY-SA 2.0, via Wikimedia Commons
- Golden wonder killifish Marrabbio2, CC BY-SA 3.0, via Wikimedia Commons
- Red-tail dwarf puffer Neale Monks (English Wikipedia), CC BY-SA 3.0, via Wikimedia Commons
- Everglades pygmy sunfish Brian Gratwicke, CC BY 2.0, via Wikimedia Commons
- Neon tetra Holger Krisp, CC BY 3.0, via Wikimedia Commons
- Cardinal tetra CHUCAO, CC BY-SA 3.0, via Wikimedia Commons
- Black neon tetra Debivort, CC BY-SA 3.0, via Wikimedia Commons
- Green neon tetra Sascha Biedermann, CC BY-SA 2.5, via Wikimedia Commons
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