Golden Pencilfish

With its slim, elongated pencil-like body, the golden pencilfish looks different from the tetras. Its golden-yellow body carries a thick black stripe running from the snout to the tail, with a thin gold line above it; bright red patches appear on the males' fins. At night the main stripe fades and dark blotches appear on the body; this is a normal night coloration typical of pencilfish.

It is the most widely available and hardiest species among the pencilfish. With its small mouth and calm nature it suits planted nano and community aquariums.

It lives in slow-flowing streams, swamps and planted shoreline areas along the northeastern coast of South America and in the lower Amazon basin. It is usually found among dense vegetation and roots, close to the surface.

• Volume: at least 54 liters for a group of 6–10.
• Water: 24–27°C, pH 6–7.5, soft to moderately hard water.
• Lid: small but a good jumper; a lid is needed.
• Decor: dense plants, floating plants and roots; gentle flow. Pencilfish become stressed in a bright, bare aquarium.

Because its mouth is very small, the food must be fine. Fine flakes, micro granules, frozen cyclops, daphnia and newly hatched brine shrimp are suitable. It usually takes food from the surface and middle water; it rarely picks up food that falls to the bottom.

Peaceful and calm. Males set up small territories and display to each other by spreading their fins; these displays are harmless. It does not bother other species and leaves adult shrimp alone.

Good companions: small tetras, rasboras, corydoras, otocinclus, dwarf cichlids, dwarf gouramis, shrimp.

Avoid: fast, greedy species (it falls behind at feeding time), fin nippers, large predators.

It does not form a tight school but lives in loose groups: at least 6, ideally 10 individuals. If there is more than one male, planted areas should be left where each can set up a small territory. A female-heavy ratio reduces chasing.

It is an egg scatterer and can be bred in the aquarium. A separate tank is prepared with soft, slightly acidic water and fine-leaved plants or moss; the pair lays a small number of eggs over several days. Because the parents eat the eggs, either the eggs or the parents must be removed. The fry are very small and are fed infusoria.

• Underfeeding: fish kept with fast species can go hungry; watch them at feeding time.
• Jumping: losses occur in tanks without a lid.
• White spot (ich): may appear after transport.

Males are slimmer and more colorful; the red patches on their fins are distinct and the tips of their pelvic fins are light-colored. Females are plumper and paler, with faint red on their fins.