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.


Dwarf Pencilfish
Male Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish
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℃

Natural Habitat

Japurá River
Demerara River
Essequibo River
Nickerie River
Rio Napo


In the home aquarium, the Dwarf Pencilfish will readily accept most good quality dried foods such as granules, flakes and sinking pellets. These modern food products have been developed to provide all adequate nutrition to maintain your fish's health and dietary requirements.

Providing additional foodstuffs such as live, frozen, and freeze-dried meals such as bloodworm, daphnia, and tubifex once or twice a week will provide additional benefits to your fish's health and well-being but is not a must for this fish.

It should be noted that bloodworms should only be given as an occasional treat and should not be used as the staple diet as they are difficult for fish to digest and can potentially cause blockages.

This fish is an omnivore in the wild, meaning it will consume some vegetable matter. Although most modern fish foods take this into account and include them in their products, you can still supplement your fish's diet with blanched vegetables such as spinach, broccoli, and zucchini. Ensure you do not overfeed your fish and remove any leftovers the following day.

Tank Mates

2 interesting tank mate ideas for the Dwarf Pencilfish could include:

Cardinal Tetra(Paracheirodon axelrodi)
Ivantsoffs Blue Eye Rainbowfish(Pseudomugil ivantsoffi)

Sexual Dimorphism

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.

Other Pencilfish of interest

Barred Pencilfish(Nannostomus espei)
Cenepa Red Pencilfish(Nannstomus sp)
Coral Red Pencilfish(Nannostomus mortenthaleri)
Golden Pencilfish(Nannostomus beckfordi)
Hockeystick Pencilfish(Nannostomus eques)
Purple Pencilfish(Nannostomus rubrocaudatus)
View all Pencilfish
Date Added: 23/08/2020 - Updated: 08/08/2022 15:42:10