Zipper Pencilfish
The zipper pencilfish is also known as the diptail pencil fish and hockey stick pencil. Oh – it is also called the rocket pencilfish. Each name fits. Half the time the zipper pencil is pointing up like he is ready to take off like a rocket. Of course, the other half of the time his head is pointed down like he is going for a crash landing. In a school, these fish hover at alternating 45 degrees, creating the famous zipper pattern. We recommend the purchase of at least six to see this visual effect!
Quick Facts
| Scientific Name | Nannostomus unifasciatus |
|---|---|
| Origin | Colombia and the Amazon basin |
| Care Level | Moderate |
FAQ
What makes the zipper pencilfish unique in appearance?
The zipper pencilfish is known for its alternating head positions — half the time pointing up like a rocket, and half the time pointing down like a crash landing. When kept in groups, they create a distinctive zipper-like pattern as they hover at 45-degree angles.
How many zipper pencilfish should I keep in my aquarium?
We recommend keeping at least six zipper pencilfish to observe the full zipper pattern effect in a school.
Where do zipper pencilfish originate from?
They are native to Colombia and the Amazon basin.


Brandon Hamilton –
I bought six zipper pencilfish for my 20-gallon tank. The way they move in a school is absolutely mesmerizing. They constantly shift direction, creating a dynamic, flowing pattern. Very active and easy to care for. Perfect for a small community tank.
Nathan Paige –
The fish are colorful and show off their unique movements. I’ve had them for three months and they’re still active. I didn’t expect such a visual display. Only downside is they need a well-maintained tank with stable water conditions.
Diana Fisher –
Great addition to my aquarium. The zipper pattern is something I’ve never seen before. They’re peaceful and don’t fight with other fish. I now have a full school of six and it’s a highlight of my tank.