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Nannostomus marginatus
Dwarf Pencilfish

 Age of Aquariums > Freshwater Fish > Dwarf Pencilfish - Nannostomus marginatus

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Nannostomus_marginatus_2.jpg (88kb)
Photo Credit: Jon Hart

Name: Nannostomus marginatus
Size TankpHTemp
Origin: Surinam, Guyana
4 cm 40 L 6.8 25C


These are such wonderful little fish! They stay tiny, and they are very peaceful. They eat flake and live brine shrimp, and seem to like both foods equally. These little guys like to hover quite a bit, and when I had them I rarely saw them swim. Pencilfish are a cousin to the tetra, which is kind of interesting because they exhibit some of the same traits, such as fading once the tank lights are turned off, and taking awhile to "color up" once the light is turned back on. If you've got a small tank, and would like something a little out of the ordinary that won't break your bank, pencilfish may be exactly what suits your needs.

Contributed by Shawna

A shy, peaceful fish which needs a well planted tank where it swims in all water levels. This fish possesses interesting body markings. One of the more colourful of the pencil fish. Not very active but, even when stationary, its pectoral fins can be seen beating rapidly to keep it hovering in one place. When frightened, it moves very rapidly. Very difficult to breed. Requires temperatures of 23-27C to breed. Adults may eat the eggs.

Contributed by Keir Arney

I have had my pencil fish for 3 months now and they are great, but they can jump out of the tank sometimes. Mine jump out right in front of me when I do a water change.

Contributed by a visitor

One of the most interesting of the pencil fishes. They are unfortunately rarely available, at least in the Mid West USA. I have only found a single specimen for sale in the Chicago area. Marginatus proved easy to care for in a peaceful community aquarium, populated with other characins. I have maintained this individual in fairly hard tap water for several years now. Being alone has not bothered him as he usually hangs out with other pencil fishes in the aquarium.

Contributed by Robert Richmond

I have 8 of these fish in a 75 L with a pair of breeding Apistogramma Hongsloi. They like to hover above the breeding site in the Pogostemon stellata, but have gracefully handled the female's occasional discontent with them being there. In this case it seems they enjoy hiding in plants with leaves similar in shape and color to themselves enough to put up with the badgering. Keep them in a well-planted tank to reduce stress, as they are rather shy.

I've read that they need their food finely ground, but this hasn't seemed to hold true. They can eat things far larger than you'd expect their tiny mouths could handle, although smaller pieces would probably be easier on their digestion. I wouldn't recommend feeding large blackworms (or other similarly-sized foods) as they tend to struggle with them, it would be best to keep your worms poorly fed and thin if you intend to use them. Otherwise, they've readily accepted all live, frozen, flake and freeze-dried foods I've offered. They're very peaceful and hardy fish on the whole, although rather inactive. During feeding time they perk up, but otherwise prefer to chill out in the vegetation.

For dithers they've been perfect and have never bothered the fry, but if you're looking for liveliness then I'd suggest steering more towards tetras or rasboras.

Contributed by Charlene

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