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Maximum size : 4 cm

Purple Pencilfish - Nannostomus rubrocaudatus : Complete Fish Profile & Care Guide

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The Purple Pencilfish (Nannostomus rubrocaudatus) is a serene and visually captivating species that brings charm to planted aquariums and blackwater biotope setups. These Pencilfish thrive when kept in groups of ten or more individuals, with a higher ratio of females to males to minimize territorial conflicts. Due to their energetic nature, a spacious aquarium is recommended, especially when housing them with other species. Compatible tankmates include peaceful medium-sized Characins, Corydoras, Aspidoras, and smaller plecos. Purple Pencilfish also serve as excellent companions for Apistogrammas and other South American Dwarf Cichlids.

Creating a suitable habitat for Purple Pencilfish involves a heavily-planted aquarium with a dark substrate and ample hiding places. Floating plants, dried leaf litter, and driftwood branches contribute to a natural and inviting environment. Gentle water movement provided by an air-powered sponge filter is sufficient, and it is crucial to maintain stable water conditions in a mature aquarium.

Admire the striking beauty of the Purple Pencilfish as its reddish-purple hues blend with the dark stripes along its sides. Males exhibit vibrant red fins, while females display smaller red spots and silvery stripes. Appreciate the allure of these Pencilfish as they add a touch of elegance to their aquatic realm.

Purple Pencilfish Photos

Sexual Dimorphism

Distinguishing between male and female Purple Pencilfish is relatively straightforward. Males exhibit a sleeker and more vibrant appearance, showcasing their distinctive colouration and pattern. In contrast, females possess a modified anal fin, a key visual characteristic that differentiates them from their male counterparts.

Quick Facts

Scientific NameNannostomus rubrocaudatus
Year Described2009
Other NamesPurple Dwarf Pencilfish, Double Red Pencilfish
Max Size4 cm
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 10+
LifespanUp to 5 Years

Water Parameters

Water TypeFreshwater
PH4.0 - 7.0
GH2 - 12
TDS18 - 90
75 - 82
23 - 27

Natural habitat

The vibrant waters of the Marañón, Morona, and Santiago Rivers in Peru are an underwater paradise that the mesmerizing Purple Pencilfish inhabits. These captivating creatures dwell in the tranquil tributaries that meander through lush landscapes, embracing the slow-flowing currents. Venture into their realm, adorned with dense clusters of aquatic vegetation, submerged wood, and a tapestry of scattered leaves. It is within these enchanting habitats that the Purple Pencilfish finds its home, effortlessly blending in with the vibrant tapestry of nature's brushstrokes.

How to breed the Purple Pencilfish

Breeding Purple Pencilfish in the home aquarium requires a carefully planned setup. While observing fry in a lightly stocked aquarium with abundant dense vegetation is possible, maximizing the yield calls for a more controlled approach. For those with limited space or a preference for segregating adult fish, an additional tank with mature water should be established. This auxiliary tank, filled with java moss and other fine-leaved aquatic plants, can function without artificial lighting or filtration. However, if desired, a small air-powered sponge filter can be introduced.

When introducing adult fish to the breeding tank, caution must be exercised to prevent male aggression. It is advisable to avoid housing two males together, as territorial disputes may arise. Instead, pair males with pre-existing females or provide ample plant material to establish individual territories. Within a day or two, the appearance of fry can be expected.

Regular monitoring of mops is essential to maximize the growth and development of the fry. Once eggs are identified, the mops should be carefully relocated to a separate container. Initially, the fry should be offered a nutritionally balanced small-sized dry food. After approximately eight weeks, the diet can be supplemented with microworms and baby brine shrimp. During this time, the fry will start displaying their distinct colouration and patterning, further enhancing their visual appeal.

Diet & feeding

Purple Pencilfish is naturally inclined to feed on a diet consisting of small invertebrates and zooplankton. In the controlled environment of an aquarium, these Pencilfish can be easily nourished with high-quality dried foods suitable for their size. However, to ensure optimal health and vitality, it is recommended to supplement their diet with regular servings of small live, frozen, or freeze-dried foods such as newly hatched brine shrimp, Moina, and grindal worms. This varied and nutrient-rich diet will help satisfy their natural feeding behaviours and support their overall well-being.

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