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. They also have unique behaviors that are different from the typical 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 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:

– The hockeystick, diptail, and brown pencilfish are called N. eques. – Beckford’s pencilfish is also known as N. beckfordi. – Both the red and gold versions of the pencilfish include Coral red or red arc (N. mortenthaleri), – Dwarf penguinfish (N. margaratus), Dwarf pencilfish, (N. rubrocaudatus), One-lined pencilfish, (N.trifasciatus), -lined fish (N.

While most pencilfish swim horizontally like normal fish, some like the diptail pencilfish have the amazing ability 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.

Nannostomus eques – Hockeystick or brown penguinfish

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. Adding catappa leaves can help gently acidify the water if needed.

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 red pencilfish (Nannostomus mortenthaleri)

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. 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 are Pencilfish able to eat?

It is important to provide high-quality foods for your pencilfish. They prefer small foods that either float or take time to sink because of their small mouths. 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

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. 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. 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. The eggs can now be moved to a specimen container or removed from the breeding tanks.

Eggs can hatch quickly depending on water temperature. Fry become free-swimming after the yolk sac has been absorbed. You can feed them fresh baby brine shrimp, powdered fry food and green water. It is important to maintain a high water quality. Therefore, you should make daily water changes using low pH water.

Male & 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.