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. If you’re interested in getting an unusual nano fish for your next community tank, learn about the wonderful world of pencilfish.

What is a Pencilfish?

These distant relatives of the tetra family are from the Nannostomus genus and can be found in multiple countries all over South America. Many species are available in the aquarium hobby, such as:

– Brown, diptail or hockeystick pencilfishes (N. eques). – Beckford’s or yellow pencilfishes (N. beckfordi). – Coral red and red arc pencilfishes (N. mortenthaleri). – Dwarf pencilfishes (N. margaratus). – One-lined pencilfishes (N. unifasciatus). – Three-lined penifishes (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. Since they are schooling fish, you should get at least six pencilfish of the same species. 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. Be prepared to save up if you plan on getting a larger school because prices can range from $3-25, 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. However, Beckford’s and coral red pencilfish swim in the middle of the water so be aware. Most pencilfish sold at fish stores are wild-caught and prefer tropical temperatures from 75-80degF (24-27degC) and pH from 6.5-7.5. 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 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. Apistogrammas are also good dither fish and can help shyer species hide less. So 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 does Pencilfish Eat?

Your pencilfish’s health is dependent on you providing them with high-quality food. Because of their small, upturned mouths, they do best with tiny foods that float or take a long time to sink. (To help the food stay buoyant longer, avoid having fast flow near the water surface.) 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

Although not all species are easy breedable, hobbyists have had good success with Beckford’s penguins. 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. To hide eggs from their parents, add lots of javamoss and dense foliage to the mix. Feed them well, and soon you should see spawning behavior where the male pokes the female’s belly 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. Give them fresh brine shrimps, vinegar eels and micro worms. You must ensure that your water is clean and free from any contaminants.

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

Pencilfish are simple to keep, can be used in community tanks and 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.