Care Guide for Pencilfish – Surface-Dwelling Schooling Fish

The pencilfish is such an interesting surface dweller that everyone should keep at least once. They are hardy, active fish with pointed noses and pencil-like bodies. These fish have distinct behaviors and are not like other schooling fish. The amazing world of pencilfish is a great option if you are looking for a nano fish to add to your community tank.

What are Pencilfish, you ask?

These distant relatives of Tetra are from Nannostomus genus. They can also be found in many countries throughout South America. Many species are available in the aquarium hobby, such as:

– Hockeystick, diptail, or brown pencilfish (N. eques) – Beckford’s pencilfish (N. beckfordi) – golden and red versions – Coral red or red arc pencilfish (N. mortenthaleri) – Purple pencilfish (N. rubrocaudatus) – Dwarf pencilfish (N. marginatus) – One-lined pencilfish (N. unifasciatus) – Three-lined pencilfish (N. trifasciatus)

Although most pencilfish swim horizontally, some pencilfish, such as the diptail pencilfish can swim diagonally at 45 degrees. At least six pencilfish should be purchased from the same species, as they are schooling fish. However, coral red and purple pencil fish can be feisty towards each other, so we recommend buying at least 8-10 (with a ratio of one male to two females) to lessen the aggression. If you are looking to purchase a larger school, be prepared to save as prices can vary depending on the species.

Hockeystick or brown pencilfish (Nannostomus species eques).

How to Set Up an Aquarium for Pencilfish

Pencil fish can fit in a 10-gallon aquarium, but we personally like a 20-gallon high or 29-gallon tank for them. These taller aquariums are great for displaying fish that swim at different layers, so you can get top-dwelling pencilfish, midwater fish, and bottom dwellers. (Coral red and Beckford’s pencilfish tend to swim midwater though, so plan accordingly.) The majority of pencilfish found in fish shops are wild-caught. They prefer tropical temperatures between 75-80°F (24-27°C) and pH between 6.5-7.5. If necessary, you can add catappa leaves to gently acidify the water.

While pencilfish are not notorious escapers like killifish, they may jump if startled, so make sure to get a tight-fitting aquarium lid. The ornery species, such as coral red and purple pencilfish, require a lot of live plants and tall decorations in order to minimize territorial disputes and block line of sight.

Coral pink pencilfish (Nannostomus morenthaleri).

What fish can live with pencilfish? Pencilfish do well with similar-sized, peaceful fish in a community aquarium. Corydoras and tetras are common tank mates. They are also good dither fish, which can make shyer species feel more comfortable, and help them hide less. Hobbyists love to pair them up with dwarf cichlids such as apistogrammas. Some people keep them with betta fish. However, it is possible to have them separated if they become aggressive. Finally, cherry and crystal shrimp are not recommended since pencilfish are known to predate on them.

What does Pencilfish Eat?

It is important to provide high-quality foods for your pencilfish. Because of their small, upturned mouths, they do best with tiny foods that float or take a long time to sink. To keep food buoyant for longer, avoid fast flow near water surfaces. We love feeding baby brine shrimps, cyclops, daphnias, crushed flaflakes, Easy Fry, and Small Fish Food.

Three-lined pencilfish (Nannostomus trifasciatus)

How to Breed Pencilfish

Not all species are easy to breed, but hobbyists seem to have good luck with Beckford’s pencilfish. You will need a 10-gallon aquarium with a soft pH, warmer temperature at 80degF (27degC), a sponge filter and dim lighting. You will need at least 6 people to make sure you have at most one male and one woman. Parents love to eat their eggs so make sure to add lots of javamoss, dense leaves, spawning mop and/or marble substrate to conceal the eggs. You will soon see the male poking the female’s stomach to encourage her to release her eggs. At this point, you can either move the eggs to a specimen container with an air stone or remove the parents from the breeding tank.

Depending on the water temperature, eggs can hatch quickly in 1-2 days and the fry become free-swimming in 4-6 days after the yolk sac is absorbed. Feed them powdered fry food, green water, infusoria, vinegar eels, micro worms, and newly hatched baby brine shrimp. It is important to maintain a high water quality. Therefore, you should make daily water changes using low pH water.

Male and female Beckford’s pencilfish (Nannostomus beckfordi ‘red’)

Pencilfish can be kept easily, are good in community tanks and look great against a background of aquatic plant. We hope you enjoy them as much we do. For more options to occupy the top half of your aquarium, check out our article on the 10 Best Top-Dwelling Fish for Your Aquarium.