Pencilfish Care And Breeding in 6 Easy Steps


Last updated on September 4th, 2022 at 02:35 am

Pencilfish (genus Nannostomus) are tiny freshwater fish that belong to the pipefish family. The color and appearance of its over 60 distinct species of pencilfish differ greatly, but all of its body components are slender and tubular.

The pencilfish is a little fish that may be found in areas like Thailand and Mexico. It feasts on plankton with the help of two long barbels.  Because of the location of its eyes and barbels, it swims upside down.

Pencilfish is a genus of fish in the characin family Lebiasinidae. The name was initially attributed to two varieties in the 1920s, Nannostomus eques, and  Nannostomus unifasciatus, but by the mid-1950s, it was extended to all members of the genus.

Many of the species have all become popular aquarium fish owing to their eye-catching colors, distinctive form, and intriguing personality.

This blog will go through the steps involved in breeding pencilfish, their origin, natural habitat, food, reproduction, and the challenges they face.


Pencilfish are endemic to the tributaries of many river systems in South America, notably around Santa Elena, especially in the river Rio Tigre, and in Peru The river of Rio Nanay, where this species was first seen.

It was described and discovered for the first time in 2001 by Arendt and Paepke. The Pencilfish is not included on the IUCN Red List. It is also known as Peruvian Red Pencilfish, Ruby Red Pencilfish, and Red Arc Pencilfish.

Pencilfish can also be found in shoals, defending their area vigorously. In their native habitat, they mostly consume annelids, arthropods, coelenterates, and other backboneless animals.

Pencilfish description


This fish has a long body and a sharpened snout. The pencilfish may reach a maximum size of 3 cm and survive for around five years. The two horizontal dark stripes on its gorgeous crimson body give it a broad-lined look.

The bottom half of the body is paler, if not white, than the majority of it. Males are often paler than females, and another distinguishing feature is a white spot on the bottom dorsal fin. When they reproduce, the males’ entire body gets brighter.

The difference in conduct among the females and males may also be seen, with females being more submissive than males.

Ctenochaetus Hawaiiensis (Chevron Tang)

Species profile


The pencilfish is among the more unusual sea species of fish. It is a rather small fish, only growing to approximately five inches. This fish lives in the waters around Europe, and specifically the North Sea, but it is not uncommon to see them in the Mediterranean Sea. The pencil fish is also known as the sea pencil due to its appearance.

It has a rather cylindrical body that is covered in tiny scales that look like pencil erasers. These scales are a pale yellow color, and they also have a black spot on each side of their body. This fish is quite the looker, but it is also quite a peculiar creature. It has a rather large mouth for its body, and it also has a protruding snout. This helps it to detect food that is in the sand.

The pencilfish is a carnivorous fish, and it will eat anything from flatworms to marine worms. It will also eat small crustaceans, such as amphipods. The pencilfish isn’t a picky eater at all, and it will eat pretty much anything it can fit in its mouth.

Scientific name

The scientific name of pencilfish is Nannostomus

How big can a pencilfish get (pencilfish size)?

These fish are nicknamed for their slim, pencil-like body, and they seldom grow longer than 3 inches. They are naturally calm, making them excellent additions to a community tank.

Tank size

The minimum tank size for pencilfish is 5 gallons (22 liters)


Tetras, Barbs, Rasboras, Guppies, Mollies, Corydoras, Platies, Swordtails, Bristlenose Pleco, and Dwarf Gourami.

Tank set up

It is suggested that you have some expertise with fish keeping before trying to keep a Pencilfish because this species is a little more difficult to care for. Because it is a highly sensitive fish, it is easily irritated by changes in surroundings and temperature. The best advice is to try to acclimate it in an isolation tank before releasing it into its permanent residence.

If your Pencilfish’s tank is particularly crowded and thick, the best idea is to replace their water from 25 to 50 percent every two weeks at the very least. Nonetheless, it is critical to keep a clean habitat for each of the animals you are caring for.

Acidic and soft water will substantially aid in their adaptation. It is preferable to use a peat filter. A 30-gallon tank is an ideal size. The Pencilfish is a very energetic swimmer who likes to swim on the surface of the tank. If it senses an option, it will attempt to jump, thus the fish tank must be covered.

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Adding black sand to the tank’s bottom as a substrate will allow the Pencilfish to attain its best color. Herbs, both planted and floating, will significantly improve the environment. The Pencilfish enjoys hiding in the fish tank’s décor, for example, by relaxing among some driftwood ornaments.

Are they aggressive or peaceful?

Pencilfish are peaceful fish and can comfortably live in a community tank.

Pencilfish care


The Pencilfish is a simple species to raise in a home aquarium since its tank needs are straightforward. These fish like soft, mildly acidic water with a pH of 5.5 to 7.0 and an average temperature of 72°F to 82°F. The tank should be ornamented with a variety of live plants, and also debris and rockwork for hiding spots. Because these fish are sensitive to high nitrate levels, regular water changes are required. Keep in mind that these fish are jumpers, so leave the tank covered.

What do pencilfish eat?

Pencilfish are Omnivorous and will enjoy eating little pellets, cooked fish food, flake food, frozen food, dry food, and anything eatable by fish in general.

You must provide them with a varied diet. You may offer them tubifex worms, bloodworms, soft-bodied creatures such as little and frozen mosquito larvae. With an occasional treat of frozen or live small animals like brine shrimps, it will achieve its best appearance and coloration.

Water condition

They can endure water with a pH range of 6.0 to 7.4 (an average of 6.5 is ideal) and a temperature range of 22°C – 28°C (72° – 82°F). The aquarium may be very bright or dark as you choose, although dimly lit tanks will be preferred by them over brightly illuminated ones, especially if you’re going to breed them. The color of these will be brought by a heavily planted tank including their habit.

How long do pencilfish live for (Lifespan)?

Pencil fish can live for up to 5 years

Breeding pencilfish


My circumstance illustrates the likelihood of breeding in a community tank. Small pencilfish occasionally appear in the school. Some of the fry hang out behind Cryptocoryne leaves every now and then. If you want larger numbers of fry to survive, however, you would be better off with a specialized breeding tank.

Cheilinus Undulatus (Humphead Wrasse)

Step 1: Build a breeding tank

Breeding aquariums should have a minimum capacity of 10 gallons, but 20-gallon aquariums provide the best footprint and surface area for breeding.

Ideally, the tank should be dimly lit (typically with one or two low-watt bulbs with aquatic plants) with a dark base or substrate (if you don’t want to use a substrate, then a piece of dark construction paper works well as a replacement).

Plants with fluffy leaves, such as the Limnophila sessiliflora ‘dwarf ambulia’, are great for hiding eggs and fry in the tank because they are messy and tend to hide both the eggs and fry. The Java moss is essential for breeding tanks (at least for me) since it protects eggs and fry and is also home to a number of microfauna that sustain fry during their first few days.

Step 2: Get a sponge filter

It is necessary to use a sponge filter. In addition to biological filtration, sponge filtration provides oxygenation, the growth of diverse fauna (on the sponge), and cover. Additionally, you may prevent sucking up eggs, fry, or fish when you use it.

The third step is to filter the water by using peat or adding some form of blackwater extract to the aquarium. Keep the tank at a temperature of 25°C (77°F).

The fourth step is to move the fish into a breeding tank.

During this period, gradually introduce a small number of fish (a ratio of one male to two females) into the breeding tank.

You would be better off having twelve fish, four males, and eight females, for a better chance of success. As soon as the fish are in the tank, gradually raise the temperature to 29°C (84°F). In addition to the integrated blackwater extract, keep a backup supply of pre-warmed, aerated (air stones typically work) water on hand. In addition to water changes, this also benefits water aging. Using pre-made water has worked well for me.

Step 5: Feeding

It is recommended that you feed them live food, such as featherless Drosophila (or small and soft-bodied insects). The natural cycle should begin once the water in the dark tank has begun to warm up and the fish are sufficiently nourished.

Copadichromis Mbenjii (Haplochromis Quads)

Initially, males will show themselves either to each other or to females. The male will drive the female into more plants and niggling her belly as he drives her. During this stage, she ejects an egg that is fertilized by the male.

All egglayers share one characteristic: their parents are ravenous after courting, so all those eggs are delicious, healthy snacks to them. Because most eggs will get buried in the muck and the parents will never see them, I place messy plants in the tank, such as Java moss or dwarf ambulia.

Another strategy is to use marble substrates, which may also be effective by causing the eggs to fall into locations that even the parents are unable to reach.

The sixth step is to remove the parents

Once the breeding process is completed, remove the parents as soon as possible (normally in the early morning). After the parents and other fish have been removed from the aquarium, the challenging phase begins.


Protozoa, skin flukes, worms, bacterial infections, and illnesses can all affect the Pencilfish. Anything you put in the aquarium might get them sick. It is best to minimize stress; hence, stress is the primary predictor of illness.

So, provide the finest environmental circumstances for them to feel as if they are in their original habitat, and you will have no trouble raising happy and healthy fish.

Do they make good pets?

Yes. The “coral red pencilfish” or Nannostomus mortenthaleri, a brightly colored tiny characin from Peru’s Rio Nanay basin, may be the ideal aquarium fish. It’s robust, easy to care for, consumes almost any food supplied, adapts to most water conditions, and isn’t too difficult to reproduce in captivity.