Care Guide for Pencilfish – Surface-Dwelling Schooling Fish

The pencilfish is an intriguing surface dweller and should be kept at least once. They are hardy, active fish with pointed noses and pencil-like bodies. Plus, they exhibit unique behaviors that differ from your typical schooling fish. Learn more about pencilfish, a unique nano fish that you can get for your community tank.

What are 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).

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. Coral red and purple pencil fish can be aggressive so we recommend at least eight to ten (with one male to two women) to reduce 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. 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. Apistogrammas are also good dither fish and can help shyer species hide less. So hobbyists often pair them with dwarf Cichlids. Although some people have succeeded in keeping them with bettas, you should be ready to remove them from the tank if they are too aggressive. Finally, cherry and crystal shrimp are not recommended since pencilfish are known to predate on them.

What are Pencilfish able to eat?

Providing lots of high-quality foods is the key to keeping your pencilfish healthy. 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. 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. Next, get a group of at least six to ensure you have at least one male and one female. 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. After feeding them, you will begin to see spawning behavior. The male pokes the female in the stomach to encourage her egg release. The eggs can now be moved to a specimen container or removed from the breeding tanks.

Eggs can hatch in as little as a day depending on the temperature of the water. The fry will become free-swimming within 4-6 days. 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 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.