Types of Pencil Fish – 7 Nannostomus Species

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If you’re a fish lover, the Pencil fish should be right up your alley. These tiny swimmers are energetic, cute, and like to live in rather large groups for protection and comfort. They require a sizeable living space since Pencil fish are inquisitive and energetic and love to cover large distances when swimming and exploring their environment.

They are a shoaling species, meaning that they love to remain in a group for safety and will occasionally school if threatened.

The problem is that the Pencil fish is a more sensitive species, in need of proper care and regular maintenance. It’s not a fitting species for a beginner but rather for intermediate fish keepers who already know the basis of fish care.

Here are 7 of the most popular Pencil fish species that you may consider for your tank:

1. Dwarf Pencil Fish

This tiny guy barely reaches 1 inch in length, making it one of the smallest of its kind. It has a slim and elongated body with big eyes and transparent, slightly colored fins.

Origin – The Dwarf Pencil fish is mostly popular in Guyana. This freshwater fish enjoys fast-flowing streams, typically spending its time in small rivers branching from the main streams.

Size – The fish will grow no more than 1 inch in size. This small size is a disadvantage in the wild since it makes it prone to a variety of predators. This is why the Dwarf Pencil fish resorts to shoaling and schooling behavior to remain safe and improve its survivability in the wild.

Appearance – The bullet-like body displays 2 longitudinal black stripes from head to tail, with the lower one being more intense and well-defined. You may also see red across the like and on its abdominal and dorsal fins. The pectoral fins and tail are completely transparent.

Diet – The Dwarf Pencil fish is omnivorous, like all Nannostomus species. Their small mouths only allow them to eat small prey like daphnia, small crustaceans, tubifex and blood worms, etc. In captivity, they most certainly require supplementation to ensure they get all the nutrients they need to remain healthy long-term.

Behavior – The Dwarf Pencil is peaceful but extremely energetic and inquisitive. You will rarely see it in any other state than torpedoing through the tank and roaming through its environment. It is friendly towards other fish species, but a balanced male-to-female ratio is necessary to prevent male aggression.

Tank Requirements – The optimal temperature rests between 73 to 78 °F and 8 dGH water hardness. Fortunately, the Dwarf Pencil fish is highly adaptable and disease-resistant but doesn’t cope well with environmental fluctuations. Change its water regularly, keep the temperature stable, and the fish will thrive.

Compatible Tank Mates – They make ideal tank mates for smaller fish species that don’t see them as prey. These include species like cherry barb, neon tetra, bristlenose pleco, glass catfish, white cloud mountain minnow, harlequin rasbora, etc. Avoid pairing them with predatorial species like angelfish, large gourami species, and large catfishes.

Interesting facts – The Dwarf Pencil fish changes its coloring at night. Its horizontal strips will become less visible and paler compared to daytime.

2. Golden Pencil Fish

The Golden Pencil fish stands out thanks to its vivid colors and exhilarating personality. This species ranks high on the market thanks to the intense coloring and shoaling behavior that will enlighten any aquatic environment.

Origin – You can find the Golden Pencil throughout North America, as well as Guyana, French Guiana, and vast territories in Venezuela and Brazil.

Size – The fish will typically reach sizes of up to 1 to 1.3 inches, but they can even double in size in some cases. The variation has a lot to do with environmental factors and available food.

Appearance – As a Nannostomus fish, the Golden Pencil displays a familiar look. The 2 longitudinal black stripes are clearly visible, traversing the fish’s entire body. It’s the coloring that separates this species from others in the genre. The Golden Pencil irradiates orange and gold which tend to sparkle in the sun, making for a unique and eye-catchy presence.

Diet – Omnivorous. Just like any other Nannostomus representative, the Golden Pencil thrives on a varied diet comprising several species of invertebrates, zooplankton, and various worms. These fish are tiny predators in their own right with a sizeable appetite. In captivity, they require a varied diet to remain healthy in the long run.

Behavior – The Golden Pencil is a generally peaceful creature, so long as nobody invades its space. That’s because this species is rather territorial and might bully and harass other fish that may enter their comfort zone, which are the deeper areas of the tank. Males may also exhibit violence towards one another when competing for females.

Tank Requirements – The ideal temperature is around 70 to 80 °F and the tank should come with a darkish substrate for a plus of comfort. The Golden Pencil prefers slow-moving waters and a plant-rich habitat, providing them with hiding and a lush environment to explore.

Compatible Tank Mates – The Golden Pencil fish will do well in a community tank lacking large or bottom-dwelling fish. The former may seem them as prey, while the latter will invade their preferred living space. Other than that, you can pair them with fish species similar in size, diet, environmental conditions, and behavior.

Interesting Facts – You need at least 10 fish to reduce their aggression towards themselves and other fish. It’s also a good idea to pair them with energetic fish, which will keep the Golden Pencil engaged and healthy over the years.

3. Three-Stripped Pencil Fish

The Three-Stripped (Three-Lined) Pencil fish is similar to other species in the Nannostomus genre, with one considerable feature that stands out – the 3 horizontal black stripes

Origin – This species is spread out in vast areas with slow-moving waters throughout Brazil, Guyana, and Bolivia.

Size – The fish can reach sizes of up to 2.5 inches, which is significantly more than other Nannostomus species. Generally speaking, the fish will reach average sizes of 1.6 inches.

Appearance – Small, hydrodynamic body, with 3 longitudinal stripes traversing its entire body. The third stripe traverses its belly and it’s significantly smaller than the other 2.

Diet – A varied, omnivorous diet, generally consisting of insects, algae, and detritus worms. This species’ eating habits make it ideal for aquariums, as they contribute to improving the water quality and keeping the tank clean. They also thrive on regular fish food, either homemade or commercially bought.

Behavior – Energetic, shoaling, active during the day, and overall peaceful, but with visible territorial tendencies. Since the Three-Stripped Pencil fish prefer to live in groups of minimum 10 individuals and prefer to roam the middle-to-upper tank areas, they might get into conflict with other fish species occasionally.

Compatible Tank Mates – Just like previous species, the Three-Striped Pencil fish will do well in community tanks with non-aggressive tank mates.

Tank Requirements – The Three-Stripped Pencil fish enjoys water temperatures between 75 to 82 °F, medium lighting, and requires regular maintenance and care.

Interesting Facts – The fish’s distinctive coloring pattern breaks its body’s visible composition at nighttime, in darker waters. This will make the fish harder to spot by predators.

4. Coral Red Dwarf Pencil Fish

This is a mouthful of a name, but it’s necessary. The Coral Red Dwarf Pencil fish is a rare beauty in the genre with a sharpened front size of the body and a blood-red color of unparalleled beauty.

Origins – Mostly widespread in South America, throughout Peru, and neighboring areas. The fish’s high environmental adaptability has allowed it to inhabit a variety of habitats.

Size – This species of Pencil fish will reach around 1.5 inches in length, which is typical for the genre.

Appearance – The 2 familiar stripes are clearly visible along the slim and slightly pointy body. The fish will also display an intense red coloring, making it shine like a floating ruby among the tank’s dark and light-green plants.

Diet – Omnivorous. The Coral Red Pencil fish will mostly eat anything that fits their tiny mouths. This includes fish flakes, tablets, pellets, various invertebrates, zooplankton, etc.

Behavior – Overall peaceful. The Coral Red Pencil fish is typically shy towards other species, as it will avoid any confrontation or food or territorial competition. However, Coral Red Pencil males may become aggressive towards one another. Keeping them in a slightly larger tank will mitigate the problem.

Compatible Tank Mates – Preferably small fish species, displaying peaceful and non-combative behavior. Coral Reds are typically slower and won’t compete for food or territory with other fish. More aggressive and territorial fish species may scare them and even force them into hiding.

Tank Requirements – The ideal temperature should range between72 to 82 °F with moderate water movement. The fish needs environments with low lighting and a minimum of 15-20 gallons of water for a basic shoaling group of around 10 fish.

Interesting Facts – Although the fish eat and spend most of their time near the tank’s floor, they will sometimes reach the water’s surface for some acrobatics. As known jumpers, these fish won’t shy away from leaping out of the tank if given the opportunity.

5. Brown Pencil Fish

It is small, slender, brown, with a dark-brown stripe traversing its body muzzle to tail. The Brown Pencil fish isn’t as impressive as other species in the genre, but it has a distinct and unique personality nonetheless.

Origins – Throughout South America, typically in the Amazonian basins around Colombia and Guyana.

Size – Around 1.5 to 2.5 inches. This makes the Brown Pencil fish slightly larger than many of its counterparts.

Appearance – The Brown Pencil fish is astoundingly…brown. Its slender body displays different shades of brown to the point where only one stripe is visible. The dorsal stripe just blends in the color pattern.

Diet – Omnivorous. The Brown Pencil fish can eat anything that any omnivorous fish species will consume. So long as it fits its tiny mouth, that is. You should break its food into smaller pieces to help the fish consume it.

Behavior – Peaceful and timid. They aren’t as territorial as other Nannostomus species and prefer to live in smaller groups of around 6 individuals.

Compatible Tank Mates – You should keep them with other fish of similar behavior to prevent the Brown Pencil fish from going full introvert mode. More energetic fish will cause the Brown Pencil fish to retreat into hiding.

Tank Requirements – Ideal water temperature sits between 74 to 84 °F, which is slightly higher than other tropical fish. They also prefer darker substrates and will accommodate just nicely to smaller environments.

Interesting Facts – The Brown Pencil fish will eat most if not all of its eggs upon spawning. To prevent this, provide them with a plant-rich breeding tank and remove the female once it has finished laying the eggs.

6. One-Lined Pencil Fish

The One-Lined Pencil fish is different from other Nannostomus species, both regarding looks and diet.

Origins – It is widespread around Brazil, Bolivia, Colombia, Venezuela, and Guyana.

Size – The One-Lined fish can reach up to 2.8 inches, which is double than most of its Nannostomus counterparts.

Appearance – A long, slender, and silver body with a black stripe running it muzzle to tail. All of its fins are transparent, and the fish won’t display any other colors except silver and black.

Diet – Unlike other Nannostomus species, the One-Lined Pencil fish is carnivorous. The fish requires a diverse diet in captivity, consisting of both live and frozen fish food.

Behavior – The One-Lined Pencil fish is shy and peaceful and won’t get along with overly aggressive or large species. Also, keep in mind that this fish is carnivorous despite its small size. Don’t pair it with smaller fish, or the One-Lined Pencil fish might hunt them.

Compatible Tank Mates – Fish of similar size and behavior. Pair them with peaceful fish that aren’t too territorial or inquisitive by nature.

Tank Requirements – The temperature should remain between 72 to 82 °F with minimal variations as much as possible. You also need a filtration and a heating system to provide the fish with stable living parameters.

Interesting Facts – The One-Lined Pencil fish has an abnormal swimming pattern called the oblique style.

7. Barred Pencil Fish

This fish species is one of the few Nannostomus species that don’t come with the standard black stripes.

Origins – The fish has been mostly spotted in the Mazaruni River in Guyana and several canals in Venezuela, the latter which still require confirmation.

Size – Around 1 inch. This tiny, energetic, and handsome fish is one of the smallest in its genre.

Appearance – Light yellow color with transparent fins and dark spots traversing the body longitudinally.

Diet – The Barred Pencil fish is carnivorous and will thrive on a diverse diet consisting of live food, fish flakes, tablets, etc. In the wild, the fish ranks as a micro-predator.

Behavior – Peaceful, timid, and easy-going. It’s a great choice for beginners, thanks to its friendly personality.

Compatible Tank Mates – The Barred Pencil fish prefers the company of its own species. Placing it in a community tank might stress it out and bring out its timidity.

Tank Requirements – The ideal temperature is around 72 to 82 °F with water hardness between 18 and 90 ppm. Keep its tank clean and change the water regularly to ensure the fish’s health long-term.

Interesting Facts – You need at least 12 of them to make them feel comfortable in their environment.


There are numerous types of Pencil fish available, each with their own personality, environmental preferences, and special features. Make sure you provide your favorite species with the optimal living conditions. The Pencil fish isn’t really a beginner-friendly species, so you might want to do more research before getting them.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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