Care Guide for Pencilfish – Surface-Dwelling Schooling Fish

Pencilfish are fascinating surface dwellers that every person should have at least once. These hardy and active fish come with pointy snouts and slender, pencil-like bodies, as described by their common name. 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?

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 just like other fish. However, diptail pencilfish like the diptail pencilfish are able to swim diagonally at a 45 degree angle. 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. You will need to save money if you want to buy a bigger school. Prices can range from $3-25 depending on species.

Hockeystick or brown pencilfish (Nannostomus 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. However, Beckford’s and coral red pencilfish swim in the middle of the water so be aware. Most pencilfish that are sold in fish stores are wild-caught. They like tropical temperatures between 75-80degF (24-25degC) with a pH of 6.5 to 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. To minimize territorial disputes, ornery species like coral red and purple penguins require lots of plants and tall decorations.

Coral red pencilfish (Nannostomus mortenthaleri)

What fish can live with pencilfish? Pencilfish do well with similar-sized, peaceful fish in a community aquarium. Common tank mates include corydoras, tetras, and rasboras. 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. While some people have successfully kept them with betta fish, be prepared to separate them if the betta is too aggressive. Because pencilfish have been known to predate upon crystal and cherry shrimp, they are not recommended.

What do Pencilfish Eat?

Providing lots of high-quality foods is the key to keeping your pencilfish healthy. Because of their small, upturned mouths, they do best with tiny foods that float or take a long time to sink. Avoid fast flowing near the water’s surface to keep the food 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. You will need at least 6 people to make sure you have at most one male and one woman. 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. You will soon see the male poking the female’s stomach to encourage her to release her eggs. You can then either transfer the eggs to a container with an airstone or take the parents out of 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.

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.