Beckford's Pencilfish (Nannostomus beckfordi)

Nannostomus beckfordi, Beckford's Pencilfish, is the most commonly available and arguably most adaptable member of the pencilfish family. Native to a wide range of South American river systems — from the lower Amazon and Guyana to Trinidad — it is found across a broader geographic and ecological range than most pencilfish, which contributes to its greater hardiness and adaptability in captivity.

The fish displays a classic pencilfish form: a slender, elongated body with a distinctive metallic gold to orange-red stripe running from the snout to the base of the tail. The upper body is olive-brown and the belly is pale cream. Males develop vivid red colouration in the fins, particularly the anal, ventral, and caudal fins, especially when in spawning condition or displaying to other males.

Pencilfish are characterised by their unusual nocturnal resting posture — they tilt their bodies head-down at an angle of approximately 45 degrees when at rest at night, a behaviour unique to the group. During the day, they swim in a normal horizontal position.

Beckford's Pencilfish is ideal for planted aquariums with soft to moderately hard water. Unlike some pencilfish that require very soft, acidic conditions, beckfordi adapts well to a wider range of water chemistry. It is a mid-water to surface species and pairs beautifully with bottom-dwelling corydoras and mid-water small tetras.

Tank Setup: A 40-litre minimum for a group of six. Dense plantings with fine-leaved plants (Java moss, Hornwort, Myriophyllum) at the sides and back, open mid-water swimming space, and floating plants to diffuse top lighting. Gentle water flow — use a sponge filter or output diffuser.

Water Parameters: Temperature 23–28°C; pH 5.5–7.5; GH 2–15 °dH; KH 1–8 °dH. More adaptable than most pencilfish. Moderately soft to moderately hard water is acceptable.

Feeding: Omnivore favouring small invertebrates. Feed micro pellets, crushed flake, frozen baby brine shrimp, Daphnia, micro worms, and live fruit flies. Mouths are small — ensure food particle size is appropriate. Feed twice daily.

Tank Mates: Peaceful with all non-aggressive, similarly sized species. Excellent with other small tetras, small rasboras, pygmy corydoras, Otocinclus, small Apistogramma, and dwarf shrimp (adults are safe; shrimplets may be eaten).

Behaviour: Active, mid-water schooling fish during the day. Schools loosely but benefits from groups of 8+. Males display to each other with fin flaring and colour intensification. Nocturnal head-down resting posture is normal — do not be alarmed when lights first come on.

Health: Hardy for a pencilfish. Sensitive to poor water quality. Avoid elevated nitrates. Weekly 20% water changes with dechlorinated water maintain health. Rarely affected by disease if parameters are stable.