Red Pencilfish
Nannostomus rudius
Description
The Red Pencilfish is a small and striking species of pencilfish, recognized for its slender, elongated body and vibrant red coloration, particularly at the tail. The body is typically transparent to light brown with a subtle iridescent sheen, and the tail region of the fish exhibits a rich red hue, which intensifies during breeding periods. Like other pencilfish, it has a small, pointed head and large eyes, contributing to its pencil-like appearance. Males generally have more intense red coloration compared to females. These fish are peaceful, active swimmers that prefer to be in schools, which helps them feel more secure and show their full coloration. They are known for their calm demeanor, making them an excellent addition to community tanks with other small, non-aggressive species.
Habitat Origin
Native to the tropical regions of South America, particularly in the slow-moving rivers and streams of the Amazon Basin, including parts of Brazil, Peru, and Colombia. They are typically found in clear, well-vegetated waters with moderate to low water flow. In their natural habitat, they seek cover among plants and submerged wood, and they thrive in slightly acidic to neutral water.
Aquarium
Ideal Number in Aquarium: At least 6 individuals, as they are schooling fish and feel more secure in groups.
Favorite Food
Red Pencilfish are omnivores and will accept a variety of foods. They can be fed high-quality flake food, micro pellets, and live or frozen foods like brine shrimp, daphnia, and bloodworms. They also enjoy grazing on biofilm and small invertebrates in the aquarium. A varied diet ensures they remain healthy and maintain their vibrant colors.
Behavior:
Red Pencilfish are peaceful, active, and social fish that thrive in schools. They are not aggressive and get along well with other small, non-aggressive species. They are primarily mid-water swimmers, often seen darting through the aquarium in tight groups, displaying their full coloration. Their peaceful nature makes them suitable for community tanks, where they can coexist with other small fish, shrimp, and snails. Since they are schooling fish, they feel more secure in groups, and keeping them in numbers reduces stress. They can be a bit shy and may take some time to adjust to new tankmates.
Special Care:
While Red Pencilfish are hardy, they prefer stable water conditions and clean, well-filtered tanks. They do best in a tank with plenty of plants or other decorations to provide hiding spots. This helps them feel secure and allows them to express their natural behavior. Since they are not particularly strong swimmers, it is important to ensure that there are no strong currents in the tank. They also prefer dim lighting, which mimics the shaded areas of their natural environment. Regular water changes and maintaining slightly acidic to neutral pH levels are key to their well-being.
Compatibility with Other Fish:
Yes, Red Pencilfish are compatible with many peaceful species. They can be housed with other small, non-aggressive fish, such as small tetras, rasboras, and peaceful cichlids. They can also be kept with shrimp and snails. Larger, more aggressive fish should be avoided, as they may intimidate or prey on the pencilfish. It’s best to keep them with other schooling fish to mimic their natural behavior and reduce stress.
Breeding Setup
It is highly recommended to use a separate breeding tank for Red Pencilfish due to their small size and sensitivity to aggressive tankmates. A 40-liter (10-gallon) tank is ideal, providing enough space for a pair or small group to breed while allowing easy control over water quality and temperature. Maintain a pH between 6.0 and 7.5, temperature between 24°C and 28°C, and general hardness (GH) of 5 to 12 dGH. Use a gentle sponge or internal filter with low flow to keep water calm, as strong currents can stress the fish and disrupt breeding. Include fine substrate such as sand or gravel, and add live plants like Java moss, Hornwort, or Anubias, which serve as hiding spots and egg-laying surfaces. Floating plants such as duckweed or water sprite can help mimic their natural environment by creating shaded areas. Moderate lighting replicating natural conditions is ideal.
Conditioning for Breeding
To condition Red Pencilfish for breeding, provide a varied, high-protein diet including quality flakes, live foods like brine shrimp, daphnia, and bloodworms, as well as frozen options such as mysis shrimp. This diet ensures both males and females are healthy and ready to spawn. Regular small water changes of about 25% weekly help maintain excellent water quality, which is essential to reduce stress and encourage breeding behavior.
Spawning
Red Pencilfish are egg-scattering spawners. Spawning typically occurs during the early morning or late evening when water conditions are optimal. Males court females by flaunting bright red and orange hues on their fins and chasing them around. Females lay between 20 to 50 sticky eggs on plants, tank glass, or other available surfaces. Since adults do not guard their eggs and may eat them, it is crucial to remove the adult fish after spawning to protect the eggs.
Fry Care
The eggs hatch within 24 to 48 hours, depending on temperature. Newly hatched fry cling to the surfaces and absorb their yolk sacs before becoming free-swimming. Once swimming freely, start feeding the fry with infusoria, liquid fry food, or microscopic algae, followed by baby brine shrimp or other microscopic live foods. As they grow, offer finely crushed high-quality flakes or small pellets. Maintain excellent water quality with daily small water changes (10-15%), and keep temperature stable between 24°C and 28°C. Regularly monitor ammonia, nitrite, and nitrate to ensure a safe environment.
Important Notes
Red Pencilfish reach sexual maturity at 6 to 12 months. Males are slimmer and show more vivid red or orange coloration, especially during courtship, while females tend to be larger and rounder when carrying eggs. To ensure breeding success, maintain stable water conditions, avoid overcrowding, and keep the environment calm and peaceful. Stress from poor water quality, aggressive tankmates, or sudden parameter changes can negatively impact breeding and egg survival.