Pencilfish Care and Breeding Guide

This fish has a long body and it is sharped at the muzzle. The pencilfish can achieve maximum growth of 3 centimeters and can live approximately five years. It has a broad-lined appearance, thanks to the two horizontal black stripes on its wonderful red body. The lower part of the body is a bit paler or even white than the rest of it. Usually, the males are pretty much paler that the females and the other difference between them is the white blotch at their bottom dorsal fin. When they procreate, the males’ whole body becomes a lot brighter.

The difference between males and females can also be noticed by their behavior where the females are more obedient than the males.

Origin of Pencilfish


Near Santa Elena, particularly in the river Rio Tigre and in Peru – river of Rio Nanay this species was first spotted. It was first described and discovered by Arendt and Paepke in the year of 2001. The Pencilfish cannot be found on the IUCN Red List. It is also recognizable by the names of Peruvian Red Pencilfish, Ruby Red Pencilfish or Red Arc Pencilfish.

They can be seen in shoals, keeping bravely their territory. In their natural habitat, they eat mainly annelid, arthropod, coelenterate and other animal that lack backbones.

Aquarium Setup

To keep a Pencilfish, it is recommended that you have an intermediate experience in fish keeping because it is a little bit complicated to take care of this species. It is a very sensitive fish, so when it comes to changing environments and temperatures it is often prone to irritations. The best advice is to try and acclimatize it in a quarantine tank before placing it in its everlasting home.

If the tank your Pencilfish lives in, is very crowded and dense, the best advice is to change its water from 25 to 50 percent minimum every second week. Nonetheless, it is crucial to maintain a clean environment for each one of your species that you are taking care of.

Acidic and soft water will greatly help them to adapt faster. It is best to use a peat filter. The best size is about 29 gallon tank. The Pencilfish is quite an active swimmer and it will swim mostly on the top of the aquarium. If it sees an opportunity, it will try to jump so it is a must to cover the fish tank.

Adding dark sand to the bottom of the tank as a substrate will provide the Pencilfish to achieve its greatest coloration. Good planted and floating herbs will add to the atmosphere a lot. The Pencilfish loves hiding in the décor that is placed into the fish tank, for example it loves resting near some driftwood decorations.

Recommended temperature is from 22 to 27 Degrees Celsius accompanied with pH range from 5.7 to 7.0 and hardness range from 3 to 10 dGH. In a tank with low lightning your Pencilfish will be calmer.

Feeding Habit

Although it has a certain habit in the wild to feed on zooplanktons and little invertebrates, when it is placed in captivity, it will generally eat any kind of food. It is an omnivorous fish that means that it does not have a picky character when it comes to nourishment.

It will enjoy eating little pellets, cooked fish food, flake food, frozen food, dry food and anything eatable by fish in general. With an occasional treat of frozen or live small animals like brine shrimps and bloodworms, it will achieve its best appearance and coloration. Take a note that the Pencilfish has a very small mouth, so its food has to be offered smashed or blended to avoid injuries or choking. The frequency of feeding should be a few times a day.

Fish Temperament

The Pencilfish can live as a single or in a group with its kind, where it will feel pretty comfortable. Best number to make a group is 6 fish or more. It is highly recommended to keep more females than males in one aquarium, to prevent the aggression between the male rivalries. Too much antagonism will stress the females, so reduce the number of male Pencilfish.  Interesting fact is that this fish is not aggressive with different species so it is considered to be a good tank mate. Considering this fact, better place your Pencilfish in an aquarium with smaller fishes, hence they cannot win fighting over food with larger species and if situations like this are overlooked, the Pencilfish can easily die from hunger.

Breeding Guide

A lot of aquarists had success in the procreation of the Pencilfish. The first thing you should keep in mind is to have the best possible water conditions. In a very dense planted fish tank, the risk that the eggs will be eaten is huge so you can try spawning them in a different aquarium filled with acidic and soft water.

While breeding, the males will be very aggressive and territorial so it is best to spawn them in pairs. Try putting one pair if you have a smaller nano tank. If you have an additional larger tank of 10 gallons, you can do multiple pairings there. The tank has to be quite planted with vegetation and does not have to be very bright because the fish is very sensitive to light. From herbs, you can provide java moss, nylon spawning mops where the eggs can be laid, or clumps of wool.

The best temperature for reproducing is around 23 Degrees Celsius with a pH of 6.7 and hardness of approximately 2.

The active breeders should be fed for about 7 to 10 days with live food. Then, the spawning will begin. The female lays from 25 to 30 eggs. Afterwards, the parents should be removed and the tank has to be kept dark. The eggs hatch in about 35 hours, and three or four days later try to swim on their own.

The fry can be fed with brine shrimp and micro worms.


The Pencilfish is prone to protozoa, skin flukes, worms, bacterial infections and diseases. Anything you add into the aquarium may cause illness. It is best to reduce the stress, hence the stress is the main indicator for sickness.

So, achieve the best environmental conditions to make them feel like they are in their natural habitat and you will have no problem to raise healthy and happy fish.

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