Purple pencilfish

Nannostomus rubrocaudatus

Red-purple interstripes and a red anterior dorsal fin

Adult males can show red-purple colour between both sets of dark bands, especially at the rear. Look at fin colour as well as overall redness.

Adult length: Up to 2.6 cm (standard length, without the tail fin)
Water temperature: 24–28 °C
pH: 4–7
Hardness: 1–5 dGH

Natural habitat: Native to Peru; its precise wild habitat remains unconfirmed.

Male rivalry in cramped quarters can cause severe injury. Use mature stable water, retreats and broken sight lines; small body size does not justify a tiny aquarium.

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Appearance and identification

Red appears near the dorsal, pelvic and anal fin bases with clear outer portions. Coral red males instead show a pale patch at the front of the dorsal base.

Same-species behaviour

Keep ten or more with adequate floor area and structure.

Space requirements

At least a 90 × 30 cm base for a mixed-sex group, with dense shelter and broken sight lines.

Diet and feeding

Offer fine dry foods and small frozen or live foods; check that subordinate individuals receive food.

Compatibility limits

Watch chasing, feeding competition and size. Take particular care with similar-looking pencilfishes.

Aquarium environment

Plants and roots provide retreats and interrupt sight lines. Retain swimming room and gentle flow.

Sources