Pencilfish – Types, Care, Tank Mates Size, Feeding & Full Details!

The pencilfish belongs to the pipefish family and is a relatively small freshwater fish with more than sixty species, each with its own distinct aesthetic appeal.

These elongated, slender creatures, which are native to Mexico and Thailand, primarily feed on plankton.

The most captivating aspect of pencilfish is their peculiar swimming behavior. They have the fascinating habit of swimming upside down.

Its attractive colors and unusual movements make it a popular choice for fish enthusiasts.

Aquatic life is vast and varied, with one of its most distinctive representatives being the pencilfish. Notably, the pencilfish has managed to captivate aquarists worldwide with its unique appearance and striking colors.

This guide aims to provide an exhaustive overview of pencilfish care, breeding protocols, ideal tank setup, and disease prevention methods.

Quick Stats About Pencilfish

Scientific Name Nannostomus beckfordi
Family Lebiasinidae
Common Names Beckford pencilfish, golden pencilfish, pencil fish
Ease of keeping Medium
Lifespan up to 5 years
Tank size 5 gallons (22 litres) and more
Temperament Peaceful
Tank type Community of small fishes
Diet Omnivorous
Temperature 72- 78 °F (22-26 °C)
pH 5.0 – 8.0
Water hardness 9–20 dGH
Size Up to 3.5 cm (1,5 in)

Pencilfish Appearance

Regarded as the delicate masterpiece of aquatic artistry, the pencilfish, belonging to the family of Lebiasinidae, is a distinct creature that has consistently captured the attention of aquarists worldwide.

This tropical freshwater fish reveals a unique tapestry of colors and forms that sets it apart from its aquatic counterparts.

The pencilfish displays an elongated, slender body that measures around 3 centimeters at maximum growth. This design resembles the sleek outline of a pencil, thereby earning its distinctive name.

A remarkable characteristic of the pencilfish is its palette of radiant colors. It usually flaunts a shimmering yellow, red, or maroon hue, highlighted with a pair of bold, horizontal black stripes running along its body.

These contrasting bands imbue the pencilfish with a striking visual appeal, amplifying its artistic presentation.

A fascinating element of the pencilfish is its sexual dimorphism. The male pencilfish tend to be paler compared to the female counterparts.

Furthermore, males can be identified by a unique white blotch on the lower region of their dorsal fin, a characteristic that becomes more pronounced during the breeding phase.

However, it is the behavioral differences that make the distinction more apparent. Males tend to display more assertiveness, while the females typically exhibit more docility.

Natural Habitat of the Pencilfish

The pencilfish, as a freshwater species, is native to the warm, tropical waters of South America.

In the wild, these fishes prefer a densely vegetated environment, gravitating towards slow-moving streams and rivers, or the serene edges of floodplains.

They are often found in shoals, navigating their territory and sourcing their diet from the bountiful aquatic fauna.

The wild diet of the pencilfish consists of a plethora of tiny invertebrates and zooplankton, demonstrating their adaptability to a versatile menu.

This attribute, combined with their peaceful nature, has contributed significantly to their popularity in the community tanks of aquarists.

Origin and Distribution of the Pencilfish

Originating from the enchanting ecosystems of South America, the pencilfish was initially discovered in the rivers of Peru and Ecuador, specifically the Rio Tigre and Rio Nanay.

These tropical fish, also known as Ruby Red Pencilfish or Red Arc Pencilfish, were first described in detail by Arendt and Paepke in 2001. As of today, they are not listed on the IUCN Red List, signaling that they are not currently at risk of extinction.

Although primarily a South American species, pencilfish have gradually spread to other parts of the world due to the aquarium trade.

Today, they are raised in home aquariums and fish farms across the globe, from North America to Asia, owing to their manageable care requirements and mesmerizing aesthetic appeal.

Growth, Size & Lifespan of the Pencilfish

The pencilfish is a diminutive species, measuring around 1.5 inches or 3.5 centimeters when fully mature. Their slender, elongated physique and small stature may seem unassuming, but it adds a touch of elegance to any aquarium setup.

This fascinating species demonstrates a modest lifespan, generally reaching between four and five years under optimal conditions.

However, aquarists should note that with meticulous care, a well-maintained aquarium environment, and a balanced diet, the lifespan of a pencilfish can often be extended.

Ultimately, the pencilfish proves to be an intriguing addition to an aquatic ecosystem, appealing to hobbyists for its delicate beauty, intriguing behavior, and relatively straightforward care needs.

By understanding the essential aspects of this species, from its radiant appearance and native habitat to its geographical origins and vital statistics, aquarists can appreciate the full richness of what the pencilfish brings to their community tanks.

Pencilfish Behavior and Temperament

Easily recognizable by their sleek, pencil-like bodies, pencilfish are notable for their intriguing behavior and mild temperament.

These serene, community-friendly species typically exhibit a schooling nature and prefer to remain in shoals. During daylight hours, you may observe pencilfish swimming in the middle or lower regions of the tank, displaying coordinated movements, and engaging in playful chases with their schoolmates.

While generally peaceful, male pencilfish might display assertive behavior during the breeding season, vying for the attention of the females.

However, this behavior rarely escalates to aggression, and the peaceful ambiance of the aquarium typically remains undisturbed.

Types of Pencilfish

Pencilfish are not just a singular species, but a part of a larger group called “Nannostomus,” containing a myriad of species each with their unique traits. Here are a few types you might come across in your aquascaping journey.

Golden Pencilfish (Nannostomus Beckfordi)

Nannostomus Beckfordi, or the Golden Pencilfish, is known for its striking golden hue that glistens under suitable lighting. This species can reach up to 2.5 inches in length and has a more pronounced horizontal stripe running down the length of its body.

Dwarf Pencilfish (Nannostomus Marginatus)

The Dwarf Pencilfish, or Nannostomus Marginatus, is a tinier species, reaching only about 1.5 inches in full maturity. This species is particularly beloved for its vibrant red coloring on the lower half of its body and three distinct black stripes running down its length.

Diagonal Pencilfish (Nannostomus Eques)

Another fascinating species is the Diagonal Pencilfish, or Nannostomus Eques. This species stands out for its unique posture. Instead of swimming horizontally like most fish, the Diagonal Pencilfish tends to keep a diagonally upward stance.

One-lined Pencilfish (Nannostomus Unifasciatus)

The One-lined Pencilfish, or Nannostomus Unifasciatus, is a larger species in this group, reaching up to 3 inches. True to its name, this type of pencilfish showcases a single black stripe that runs from its snout to the tail.

Red-tailed Pencilfish (Nannostomus Rubrocaudatus)

Last but not least, we have the Red-tailed Pencilfish, or Nannostomus Rubrocaudatus. This species is admired for its fiery red tail that stands out against its silver-gray body, giving a delightful contrast.

Remember, each pencilfish species may have slightly different requirements regarding tank conditions and diet.

So, always do your research to ensure you’re providing a suitable environment for your particular type of pencilfish.

Setting Up a Tank for Pencilfish

The intricate task of setting up an aquarium for pencilfish involves a spectrum of factors.

Achieving the ideal setup can ensure their healthy growth and vibrant behavior.

Tank Size

Pencilfish are active swimmers that appreciate ample swimming space. For a small shoal of five to six pencilfish, a tank size of 10 to 20 gallons is recommended. As they are a schooling fish, a larger tank allows them to display their natural behavior more freely.

Substrate for Pencilfish

When it comes to the substrate, it’s essential to mirror the natural habitat of the pencilfish. Consider dark, fine-grained sand or soft, rounded gravel to mimic the bottom of a tropical river. This type of substrate will also support the growth of live plants, further enhancing the environment for your pencilfish.

Decorations and Hiding Spots

Creating a natural, stress-free environment is crucial for the well-being of pencilfish. Incorporate live plants, driftwood, and rocks into the aquarium to create hiding spots and replicate their natural habitat.

Floating plants can also provide shade, helping to create a serene environment.

Monitoring Water Parameters

Pencilfish thrive in specific water conditions. Maintain a temperature of 72-82°F, a pH of 5.5-7.5, and a hardness of 2-12 dGH.

Regularly test the water to ensure these parameters remain stable.

Filtration and Aeration

Pencilfish are accustomed to calm waters, so choose a filtration system that doesn’t create a strong current. Sponge filters are an excellent choice for this purpose.

Additionally, ensure the tank is well-oxygenated for the health and vitality of your pencilfish.


Pencilfish prefer dim to moderate lighting, which simulates their natural habitat. Too bright lighting can cause stress, so it’s advisable to use floating plants to diffuse the light and create shaded areas in the tank.

Tank Mates

Pencilfish are peaceful, making them excellent additions to community tanks. Suitable tank mates include other peaceful species such as tetras, rasboras, and dwarf cichlids. It’s essential to avoid aggressive or overly active fish that can stress or intimidate your pencilfish.

Feeding Essentials

Pencilfish are omnivorous and enjoy a varied diet. Feed them a combination of high-quality flake food, freeze-dried foods, and live or frozen foods like brine shrimp and daphnia. Regular feeding of a balanced diet will keep your pencilfish vibrant and healthy.

By paying close attention to these aspects, you can ensure a thriving, engaging environment for your pencilfish

Tank Maintenance Tips for a Pencilfish Tank

In order to maintain the vitality of your pencilfish and their environment, routine tank maintenance is crucial.

Let’s delve into the key steps in this process, ensuring your aquarium remains an idyllic home for these elegant fish.

Water Changes

Regular water changes are pivotal for a healthy pencilfish tank. The fresh water helps reduce harmful substances, like ammonia and nitrites, which can accumulate over time.

Aim to change 10-15% of the tank water weekly. Remember to treat the new water to remove chlorine and match its temperature with that of the tank. This way, you’ll create a clean and stable environment for your pencilfish to flourish.

Cleaning the Tank and Decorations

Over time, your tank and its decorations may collect algae and waste, impacting the overall health of the environment. Use an algae scraper or pad to clean the inside of the tank every few weeks.

For decorations, consider a soft brush to scrub off any algae buildup. Just remember to be gentle around plants and fish during the cleaning process!

Filter Maintenance

Filter maintenance is a cornerstone of a healthy pencilfish habitat. The filter helps to maintain water quality and a balanced ecosystem. Check your filter at least once a month and clean or replace the media as needed. Remember, some beneficial bacteria live in the filter. Avoid cleaning it with tap water as chlorine can kill these bacteria. Instead, rinse it in the water you’ve removed during a water change.

Monitor Fish Health

Regularly observe your pencilfish for any signs of illness or stress, such as changes in behavior, color, or eating habits.

Prompt action can often nip problems in the bud, preventing them from escalating. Keep an eye out for any signs of disease, like spots, growths, or odd swimming patterns.

If you spot anything unusual, consult a vet or aquarium expert promptly.

In conclusion, maintaining a pencilfish tank is not just about the nuts and bolts of cleaning and changing water.

It’s about creating a dynamic, healthy ecosystem that mimics the natural world of the pencilfish. And remember, you’re not just keeping fish – you’re creating a world. So let’s make it a good one!

Acclimating Pencilfish

Whenever you introduce pencilfish to a new aquarium, the acclimation process is crucial. This process allows your fish to adjust to the new water parameters and temperature, reducing stress and promoting good health.

Start by floating the bag containing the pencilfish in your aquarium for about 15-20 minutes.

This will align the temperature of the bag water to that of the aquarium. Next, gradually mix the aquarium water with the bag water over the next hour.

This slow and steady process helps the fish adapt to the water chemistry of your tank. Once acclimated, gently net the pencilfish and introduce them to their new home.

Remember, never pour water from the bag into your aquarium to avoid contaminating your tank.

Pencilfish Diet and Feeding

Pencilfish are known for their flexibility when it comes to their diet. Here’s a detailed look at what to feed your pencilfish for optimal health and vitality.

High-quality Flake Food

High-quality flake food forms the backbone of a pencilfish’s diet. It’s packed with essential nutrients that your fish need to thrive. Feed them a pinch of flakes once or twice a day, making sure they eat all the food within a few minutes.

Live and Frozen Foods

Pencilfish enjoy variety in their diet, and live or frozen foods can offer this. Foods like daphnia, brine shrimp, or bloodworms are all excellent choices. Feed these foods to your pencilfish a few times a week as a treat and nutritional boost.

Plant Matter

Pencilfish are omnivores, and plant matter should also be part of their diet. Algae-based flakes or blanched vegetables like spinach or peas can offer the necessary vegetable content.

Feeding Considerations

Keep a few things in mind when feeding your pencilfish:

  1. Quantity: Overfeeding can lead to obesity and water quality issues. Always feed what they can consume in 2-3 minutes.

  2. Variety: Varying the diet ensures your pencilfish receive a broad spectrum of nutrients.

  3. Observation: Pay attention to your pencilfish’s eating habits. Changes could signal health issues.

  4. Quality: Invest in good quality feed. The better the food, the healthier your pencilfish will be.

By following these guidelines, you’ll provide a nutritious diet that will keep your pencilfish healthy and vibrant, allowing them to live their lives to the fullest in your carefully maintained tank.

Perfect Tank Mates for Pencilfish

Choosing the right tank mates for your pencilfish is crucial. To maintain harmony in your tank, you should select fish that can coexist peacefully with your pencilfish.

Pencilfish are peaceful and get along well with similarly sized and temperament fish.

Here are a few choices that work well:

  1. Tetras: Neon tetras, cardinal tetras, or black phantom tetras are good companions. They share similar water conditions and peaceful nature.

  2. Dwarf Cichlids: Species like the apistogramma or kribensis make good tank mates as they occupy the lower part of the tank, providing enough space for pencilfish.

  3. Small Catfish: Corydoras or otocinclus are excellent choices as they tend to stay at the bottom of the tank.

  4. Rasboras: Harlequin rasboras or lambchop rasboras are peaceful and won’t compete with pencilfish.

  5. Danios: Zebra danios or celestial pearl danios are active swimmers that get along well with pencilfish.

Tank Mates to Avoid

Avoid aggressive or predatory species as pencilfish are shy and peaceful.

Here are a few examples:

  1. Large Cichlids: Such as Oscar fish or Jack Dempsey Fish.

  2. Large Catfish: Such as Pictus catfish.

  3. Predatory Fish: Like Arowana Fish or freshwater sharks.

  4. Territorial Species: Such as Red Tail Black Sharks.

  5. Larger Barbs: Like Tiger Barbs, who may nip at pencilfish.

Breeding Pencilfish and Caring for Fry

Breeding pencilfish is an engaging and rewarding experience. With the right conditions and care, you can rear a healthy generation of these lovely creatures.

Here’s a step-by-step guide:

Creating the Right Conditions

Set up a separate breeding tank with gentle filtration and plenty of plants. Pencilfish prefer slightly acidic water (pH 6.0-6.5) and a temperature of 75-82°F. Keep the lighting dim, as pencilfish lay eggs in the morning light.

Breeding Process

A healthy diet will induce breeding. Once you notice the females are fuller (a sign they’re carrying eggs), transfer a pair or small group to the breeding tank. Spawning usually happens in the morning. The female will lay her eggs on the underside of leaves or other surfaces.

Caring for the Eggs

Once eggs are laid, remove the adults to prevent them from eating the eggs. The eggs will hatch in 2-3 days.

Fry Care

Newly hatched fry can be fed infusoria or liquid fry food until they’re large enough to eat micro-worms or baby brine shrimp.

Remember to maintain good water quality during the entire process. Frequent small water changes are better than less frequent large ones.

With careful and attentive care, your pencilfish fry will grow into healthy, vibrant adults.

Decoding Stress Signs in Pencilfish

Pencilfish, like other aquatic creatures, can also exhibit signs of stress. Identifying these signs early on can help in taking necessary action to mitigate the situation.

Pencilfish may display different signs of stress, such as:

  • Hiding More Than Usual: If pencilfish start hiding more than usual or don’t come out to eat, it could be a sign of stress.

  • Unusual Swimming: Erratic swimming, swimming near the surface, or remaining stationary in one spot for extended periods could indicate stress.

  • Loss of Appetite: Pencilfish experiencing stress might eat less or stop eating entirely.

  • Changes in Color: Pencilfish might lose their vibrant coloration and appear dull when stressed.

  • Rapid Breathing: Faster gill movement than usual can be a sign of stress.

Common Health Issues in Pencilfish: Prevention and Cure

Pencilfish are relatively hardy, but like all aquarium fish, they’re susceptible to certain diseases. Here are some common health issues and their treatments:

Ich: Ich is a common freshwater disease caused by a parasite. Signs include white spots on the body and fins, rubbing against objects, and rapid breathing. Treatment involves increasing the water temperature gradually to 86°F and administering over-the-counter medication.

Fin Rot: This bacterial infection causes the fins to appear ragged. Good water quality is the best prevention. If it occurs, treat with antibacterial medicine.

Dropsy: Dropsy causes a bloated belly and raised scales. It’s often fatal and hard to treat. Maintaining excellent water quality can prevent it.

Additional Tips for a Healthy Aquarium

Keeping your aquarium healthy involves more than just routine cleaning.

Here are some additional tips:

  • Check Water Parameters Regularly: Regular testing of water parameters can help spot issues before they become serious.

  • Avoid Overfeeding: Overfeeding can lead to poor water quality. Feed only what your fish can consume in a few minutes.

  • Quarantine New Fish: Always quarantine new fish before introducing them to your main tank to prevent the spread of diseases.

Should You Get a Pencilfish for Your Aquarium?

If you’re looking for a peaceful, easy-to-care-for, and attractive addition to your aquarium, pencilfish could be a great choice.

They thrive in a community tank and add a touch of charm with their unique shape and behavior.

However, always ensure your tank conditions align with their needs for a healthy and stress-free life.

Conservation Status of Pencilfish

In the grand scheme of global conservation efforts, pencilfish have not been classified as endangered by the International Union for Conservation of Nature (IUCN).

These charming little creatures are native to South America and are found aplenty in their natural habitats. As such, they are not currently at risk.

However, like all species, their survival relies heavily on maintaining a clean, stable environment in their native waters.

Availability and Pricing

Pencilfish are widely available for aquarium enthusiasts. You can usually find them in most pet stores and online retailers that specialize in aquatic life.

Prices may vary based on the retailer, location, and specific species, but generally, pencilfish are quite affordable. As of writing, expect to pay around $2-$5 per fish.

This cost-effectiveness, combined with their peaceful nature and distinctive appearance, makes them a popular choice among aquarists.

Frequently Asked Questions About Pencilfish

Here, we answer some of the most commonly asked questions about pencilfish to help you better understand these fascinating creatures.

Question: How many pencilfish should I keep together?

Answer: Pencilfish are schooling fish. They are happiest in groups of six or more.

Question: Can pencilfish live with bettas?

Answer: Yes, pencilfish and bettas can usually cohabitate peacefully.

Question: What do pencilfish eat?

Answer: Pencilfish are omnivorous. They’ll enjoy a diet of flake food, freeze-dried food, and small live foods.


In conclusion, pencilfish make an excellent choice for both novice and experienced aquarium enthusiasts.

Their peaceful nature, distinctive look, ease of care, and affordable price point make them a winning addition to any freshwater setup.

Remember to keep your tank conditions optimal, follow the recommended feeding guidelines, and enjoy the serene beauty pencilfish bring to your underwater world.

Embrace the joy of aquascaping with pencilfish and unlock an unparalleled viewing experience.