Max Size: 3.5cm

Dwarf Pencilfish (Nannostomus marginatus)

The Dwarf Pencilfish is the smallest fish of this species. They are friendly and peaceful but can be quite timid and will hide away and refuse to eat if their tankmates are too boisterous.

They have a silver body and two black striking horizontal stripes from head to tail. They also display a distinctive red patch on the caudal fin base, between the primary and secondary dark lateral lines.

Tank Mates for the Dwarf Pencilfish

2 ideal tank mate ideas for the Dwarf Pencilfish include:

Cardinal Tetra(Paracheirodon axelrodi)
Ivantsoffs Blue Eye Rainbowfish(Pseudomugil ivantsoffi)
Quick Facts
Scientific NameNannostomus marginatus
OriginsGuyana, Suriname
Aquarium LevelMiddle - Top
Lifespan2 - 5 years
Water Parameters
Water TypeFreshwater
PH5.5 - 7.5
GH3 -10
75 - 79℉
23.9 - 26.1℃

Photos of the Dwarf Pencilfish

Dwarf Pencilfish
Male Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish

Natural Habitat

The Dwarf Pecilfish comes from the very soft acidic backwaters, tributaries, and swamplands, in Maduni Creek, Guyana, and Suriname.

You can also find this species of pencilfish in the middle to lower Amazon Basin East of the Andes Mountains in Brazil, Peru and Columbia, where they can be found in the Essequibo River, Demerara River, Nickerie River, Inírida River, Caquetá River, Ucayali River, Javari River, Putumayo River, Napo River, Juruá River, the Rio Negro, Branco River and the Trombetas River. Here the waters are almost still, shallow and crowded with thick vegetation and plenty of leaf litter.

Their natural water is stained a tea colour from the tannins in the decaying wood and leaves.

Japurá River
Demerara River
Essequibo River
Nickerie River
Rio Napo

What to feed the Dwarf Pencilfish

Dwarf Pencilfish will accept most foods offered to them, providing they are small enough for their tiny mouths.

Good quality granular or flake food will provide them with everything they will need. Still, these fish will be very appreciative of small frozen or live foods such as mosquito larvae, bloodworm, daphnia and baby brine shrimp.

How to sex the Dwarf Pencilfish

Males are more slender and more intensely coloured than the females, and some males possess a modified anal fin with the third to sixth rays being widened.

How to breed the Dwarf Pencilfish

This species can be quite challenging to breed, although there have been some success stories it is quite rare.

A separate breeding tank will be required with dim lighting and gentle air driven filtration, plenty of fine-leaved plants, and the water should be a low PH.

The substrate should be marbles or small rocks and pebbles, or you can use a mesh at the base that is big enough for the eggs to fall through but small enough that the adults are unable to get to the eggs.

When they are ready to spawn, you will see them swimming next to each other, the male will then nudge the female's abdomen, and fertilisation would have taken place.

The female's eggs will be laid, a small amount at a time which will fall onto the plants or between the substrate or mesh. This method will continue until the female has run out of eggs, usually up to 100 eggs.

Once the eggs have been laid, you should remove the parents as they are voracious egg eaters.

The eggs will hatch around 36-72 hours after they have been laid and the fry will become free swimming 3-4 days after that.

Other Pencilfish of interest

Barred Pencilfish(Nannostomus espei)
Coral Red Pencilfish(Nannostomus mortenthaleri)
Golden Pencilfish(Nannostomus beckfordi)
Hockeystick Pencilfish(Nannostomus eques)
Purple Pencilfish(Nannostomus rubrocaudatus)
Three Lined Pencilfish(Nannostomus trifasciatus)
View all Pencilfish
Date Added: 23/08/2020 - Updated: 14/04/2022 13:50:45