Max Size: 4cm

Three Lined Pencilfish (Nannostomus trifasciatus)

Three Lined Pencilfish are relatively peaceful fish. Even though they are sociable by nature, they are a shoaling rather than a schooling species with rival territorial males sparring regularly during daytime hours establishing and defending small territories. As a result, these Pencilfish are more aggressive than most congeners, and severe injury or even death may occur in confined spaces. For this reason, you should use a spacious aquarium, and the decor should be arranged so that plenty of broken lines of sight are supplied.

It would be best if you brought at least ten individuals, preferably more, because when these fish are kept in more significant numbers, any aggression will be spread between individuals. In addition, the fish will be more confident and will exhibit more natural behaviour.

Ideal tankmates for Three Lined Pencilfish can include similarly-sized, peaceful Characids as well as smaller Catfish species. You can also combine these fish with smaller Rasboras, Barbs and Dwarf Gouramis. In addition, These Pencilfish also make an excellent dither fish for Apistogrammas and other Dwarf Cichlids as they tend to inhabit the middle-to-upper levels of the aquarium and do not predate on fry. However, calm surface-dwellers such as hatchet fish are best avoided, as are larger and more boisterous species, especially in a smaller aquarium.

Keeping Three Lined Pencilfish in a heavily-planted aquarium with a dark substrate would be better. Floating plants are also a helpful addition, as is dried leaf litter and driftwood branches. These fish only need moderate water movement; therefore, a small air-powered sponge filter is more than adequate.

The Three Lined Pencilfish is a small fish with a small mouth that may or may not possess an adipose fin. Most pencilfish have distinctive daytime and nighttime colour patterns, and this species is no exception.

During the day, they have three black longitudinal stripes that run the entire length of the body, and at night, three prominent dark spots appear on the sides of the fish, extending from their back to their belly. In addition, these pencilfish have a greenish-gold colour on their back and sides, and their stomachs are silver. The dorsal, anal, pelvic, caudal fin and gill cover display red blotches that vary in size depending on where they are from.

Quick Facts
Scientific NameNannostomus trifasciatus
Other NamesThree-stripe Pencilfish
OriginsBolivia, Brazil, Colombia, Guyana, Peru
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 10+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH5.5 - 7.0
GH2 - 8
TDS18 - 215
75 - 82℉
23.9 - 27.8℃

Photos of the Three Lined Pencilfish

Three Lined Pencilfish
Three Lined Pencilfish

Natural Habitat

Three Lined Pencilfish are endemic to the Rio Negro and Rio Tabatinga in Brazil but are also widespread throughout the Amazon Basin, including Peru, Colombia, Guyana and northern Bolivia in South America. These Pencilfish inhabit slow-moving, slightly acidic waters, particularly in areas with dense vegetation or submerged woody structures and leaf litter.

You can find these Pencilfish in several different habitat types, including Overrun forests when the river floods, as well as extensive swamps that begin where tributaries meet the river's main branch. And finally, during the low-water season, they often become trapped in tiny lakes that are left behind, or they stay close to the wooded edges of the forest.

What to feed the Three Lined Pencilfish

Three Lined Pencilfish are micro predators feeding on tiny invertebrates and other zooplankton in the wild. However, in the aquarium, these fish will readily accept good-quality dried foods of a suitable size; however, you should also offer them daily meals of small live and frozen foods such as bloodworm, white mosquito larvae, daphnia, and baby brine shrimp.

How to sex the Three Lined Pencilfish

Distinguishing between the male and female Three Lined Pencilfish can be somewhat challenging as different individuals can have various patterning depending on where they originate. However, males typically have an additional row of red spots in the gold area between the middle and upper stripes. In addition, they are usually slightly slimmer and more colourful than females, but once again, this is irregular.

How to breed the Three Lined Pencilfish

Three Lined Pencilfish are relatively easy to breed, although a separate breeding tank will need to be set up if you would like to increase the fry yield.

The breeding tank should be dimly lit and contain bunches of fine-leaved plants such as Java Moss. Spawning Mops can also work just fine, as would plastic grass-like matting, a layer of glass marbles or a mesh. These mediums will give your Pencilfish somewhere to scatter their eggs.

The water will need a slightly acidic to neutral pH with a slightly higher temperature than the community aquarium. Adding an air-powered sponge filter or an air stone would also be beneficial to provide water movement and oxygenation.

You can spawn these Pencilfish in a group, with half a dozen individuals of each sex being ideal. It would be best to condition them with plenty of live and frozen foods, and then spawning should not bestow too many problems.

Alternatively, you can spawn these fish in pairs. The best way to achieve this is to condition the male and female groups in separate tanks with a good-quality diet of live and frozen foods.

Once the females are full of eggs, and the males present their best colours, select the healthiest female and the best-coloured male and place them into the breeding tank. The couple should spawn the following morning.

You can remove the adults 2 to 3 days later, and the first fry should be visible around three days after that.

It would be best to initially feed the fry with Paramecium or dry food of sufficiently small grade and then introduce the fry to microworm or baby brine shrimp once the babies are large enough to accept them.

Other Pencilfish of interest

Barred Pencilfish(Nannostomus espei)
Coral Red Pencilfish(Nannostomus mortenthaleri)
Dwarf Pencilfish(Nannostomus marginatus)
Golden Pencilfish(Nannostomus beckfordi)
Hockeystick Pencilfish(Nannostomus eques)
Purple Pencilfish(Nannostomus rubrocaudatus)
View all Pencilfish
Date Added: 04/02/2022 13:19:47 - Updated: 04/02/2022 14:13:34