Not furry, but we like them anyway.
Dwarf Pencilfish
Nannostomus marginatus
Also called Marginal pencilfish
From South America east of the Andes: Guyana, Suriname, Venezuela, Colombia, Peru, Ecuador and Brazil, including the Essequibo, Rio Negro, Napo and Ucayali systems12
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
Short, stocky scaled characin
One of the smallest pencilfish, with a shorter, chunkier body than its relatives, rather like a pencil stub. It wears three dark lengthwise stripes with a red stripe or patch whose length depends on where the fish comes from, plus a red spot at the base of the tail. Males are slimmer than females.13
Personality what they are like
A gentle and somewhat shy fish that fits best with other small, calm species. It also works well as a dither fish that encourages dwarf cichlids to come out.1
Daily activity how busy a day looks
Moves calmly among plants in the middle and lower water levels.12
Grooming and care the hands-on bits
Prefers soft, acidic water. Suggested ranges: about 22-28 C (FishBase gives 24-26 C), pH 4.0-7.0 (FishBase gives 5.8-7.5), hardness 1-10 dGH. Keep conditions clean and stable.12
Home where they are happiest
Tank of at least 45-60 cm length (about 41 litres) with dense planting, leaf litter, soft lighting and very gentle flow.12
Food basics what goes in the bowl
Feeds on tiny invertebrates. Small dried foods are taken, but daily small live or frozen foods such as brine shrimp nauplii, moina and grindal worms are recommended.1
Company who they like around
A sociable fish best kept in a group of 10 or more (FishBase gives 5 as a minimum).12
The story where it all began
Described by Carl Eigenmann in 1909, this species has several regional colour forms. A form once named as a separate subspecies has since been merged into it, and the coral red pencilfish from Peru was first described as one of its subspecies.124
Fun facts for the dinner table
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed September 2020)2
- FishBase
- Described by Eigenmann in 19092
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Dwarf 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
You might also like
Coral Red Pencilfish
Golden Pencilfish
Three-lined 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 marginatus - Seriously Fish seriouslyfish.comused for origin, size, care, diet, behaviour, colour forms
- Nannostomus marginatus summary - FishBase fishbase.seused for size, water parameters, IUCN, etymology
- Nannostomus - Wikipedia en.wikipedia.orgused for body shape, genus lifespan
- seriouslyfish.com seriouslyfish.com
Checked 2026-09-30. Text is written in our own words from these sources.