Not furry, but we like them anyway.
Three-lined Pencilfish
Nannostomus trifasciatus
Also called Three-stripe pencilfish, Three-banded pencilfish, Princess tetra
From South America: the Amazon basin in Brazil, Peru, Colombia and Bolivia, including the Rio Negro, Madeira and Ucayali, plus rivers of Guyana12
A friendly guide, not veterinary advice. For anything about your pet's health, ask your vet.
At a glance the quick version
Looks how to spot one
Slender, pencil-shaped scaled characin
A slim fish marked with three dark stripes, upper, central and lower, set against a golden body, with red patches on the flank and fins. Some forms show an extra-long red stripe. At night it puts on unusually wide slanting bars. Males are more intensely coloured, females rounder.13
Personality what they are like
Generally peaceful toward other species and a good dither fish for dwarf cichlids. Males are territorial with each other and spar, so they need space and cover; very boisterous or much larger tankmates are not a good match.13
Daily activity how busy a day looks
A calm mid-water swimmer that moves between plants and open patches.1
Grooming and care the hands-on bits
Prefers soft, acidic water. Suggested ranges: about 22-28 C (FishBase gives 24-28 C), pH 4.0-7.5 (FishBase gives 5.5-7.0), hardness 1-12 dGH (FishBase gives up to 4 dH).12
Home where they are happiest
Tank of at least 75 cm length (about 68 litres) with dense planting, wood and leaf litter, and still or very gentle water.1
Food basics what goes in the bowl
Feeds on worms, small crustaceans and insects. Offer small dried foods plus daily small live or frozen foods such as brine shrimp nauplii, moina and grindal worms.12
Company who they like around
A shoaling species best kept in a group of 10 or more.1
The story where it all began
Described by Franz Steindachner in 1876, it is one of the most common pencilfish in the hobby. Fish are exported from Peru and Guyana and some are farmed, and several regional colour forms are known.12
Fun facts for the dinner table
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed September 2020)2
- FishBase
- Described by Steindachner in 18762
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Three-lined Pencilfish. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Water changeAbout 25% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseRinse in old tank water, never tap waterevery month
Owner questions the things everyone asks
How often should I feed my Three-lined Pencilfish?
Feed small amounts once or twice a day. Furry Diary's starting plan is to feed daily, offering only what they can eat in a few minutes.1 Furry Diary plan
What does a Three-lined Pencilfish eat, and what should it never eat?
They eat worms, small crustaceans, and insects. Offer small dried foods plus daily live or frozen foods like brine shrimp nauplii, moina, and grindal worms. Never feed anything that could harm them; ask a vet or good breeder for specific no-go foods.12
How much space does a Three-lined Pencilfish need?
A tank of at least 75 cm length (about 68 litres) is recommended. Provide dense planting, wood, and leaf litter with still or very gentle water.1
What temperature, light or water does a Three-lined Pencilfish need?
They prefer soft, acidic water. Suggested ranges: temperature 22-28°C, pH 4.0-7.5, hardness 1-12 dGH. Keep lighting moderate and water still or very gentle.12
How often should I clean a Three-lined Pencilfish's home?
Furry Diary's starting plan suggests a weekly 25% water change, weekly glass cleaning, and monthly filter rinsing in old tank water (never tap water). Test water weekly. Furry Diary plan
Can a Three-lined Pencilfish live with others?
Yes, they are generally peaceful and make good dither fish for dwarf cichlids. Keep them in a shoal of 10 or more. Males may spar, so provide space and cover. Avoid very boisterous or much larger tankmates.13
How long does a Three-lined Pencilfish live?
Lifespan varies; ask a good breeder or exotic-pet vet for specific details. With proper care, they can live several years.
Can I handle a Three-lined Pencilfish?
It is best not to handle them; they are delicate fish. Use a net only when necessary, and always be gentle to avoid stress or injury.1
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Furry Diary's own starting care plan. A friendly guide, not a vet's advice.
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Dwarf PencilfishLike what we are building? Buy Archy a bone.
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- Nannostomus trifasciatus - Seriously Fish seriouslyfish.comused for origin, size, care, diet, behaviour, colour forms
- Nannostomus trifasciatus summary - FishBase fishbase.seused for size, water parameters, IUCN, diet
- Nannostomus - Wikipedia en.wikipedia.orgused for genus history, lifespan
- VCA Animal Hospitals: Feeding times and frequency for your dog vcahospitals.comused for owner questions
- ASPCA: Dog grooming tips aspca.orgused for owner questions
- ASPCA: Cat grooming tips aspca.orgused for owner questions
- ASPCA: People foods to avoid feeding your pets aspca.orgused for owner questions
- RSPCA: What to feed your rabbit rspca.org.ukused for owner questions
Checked 2026-09-30. Text is written in our own words from these sources.