Care Guide for Pencilfish – Surface-Dwelling Schooling Fish

The pencilfish is an intriguing surface dweller and should be kept at least once. The pencilfish is a hardy, active fish that has pointed snouts and slim, pencil-like bodies. This is their common name. These fish have distinct behaviors and are not like other schooling fish. You can learn more about pencilfish to find out if you would like to get a rare nano fish for your next community aquarium.

What are Pencilfish and how do they work?

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)

Most pencilfish swim horizontally as normal fish. But some, like diptail pencilfishes, can swim diagonally at a 45° angle. They are schooling fish so you need at least six of the same species. The aggression of coral red and purple pencilfish can make them aggressive, so we recommend purchasing at least 8-10. You will need to save money if you want to buy a bigger school. Prices can vary from $3-25 depending on 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. You should plan accordingly. (Coral red and Beckford’s penguins tend to swim in the middlewater. Most pencilfish you will find in fish shops are wild-caught. These fish prefer tropical temperatures of 75-80 degrees F (24-27 degC) and a pH between 6.5 and 7. If you need to soften the pH of your water, adding catappa leaves may be a good option.

While pencilfish are not notorious escapers like killifish, they may jump if startled, so make sure to get a tight-fitting aquarium lid. Coral red and purple pencilfish are ornery and require tall decorations and lots of live plants to keep their line of sight clear and avoid territorial disputes.

Coral Red Pencilfish (Nannostomus Mortenthaleri).

What fish can live with pencilfish? Pencilfish do well with similar-sized, peaceful fish in a community aquarium. Corydoras can be paired with tetras and rasboras as tank mates. Apistogrammas are also excellent dither fish and can make shyer species feel less isolated. This is why hobbyists often pair them with dwarf Cichlids. While some people have successfully kept them with betta fish, be prepared to separate them if the betta is too aggressive. Finally, cherry and crystal shrimp are not recommended since pencilfish are known to predate on them.

What do Pencilfish Eat?

Providing lots of high-quality foods is the key to keeping your pencilfish healthy. Their small, upright mouths make them able to take in tiny foods that are either floating or slow to sink. Fast flow is best to help food stay buoyant. Our favorite foods to feed include baby brine shrimp, cyclops, daphnia, crushed flakes, and 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. Next, make sure to get at least six members of your group so you have at minimum one male and one girl. The parents love to eat their own eggs, so add tons of java moss, dense foliage, spawning mops, and/or a marble substrate to hide the eggs. After feeding them, you will begin to see the female releasing 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. You can feed them fresh baby brine shrimp, powdered fry food and green water. You must ensure that your water is clean and free from any contaminants.

Female and male Beckford’s pencilfish (Nannostomus beckfordi red’)

Pencilfish are simple to keep, can be used in community tanks, and they look beautiful against the background of aquatic plants. 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.