Black Arrow Royal Tetra - Inpaichthys sp. 'Black Arrow' Fish Profile & Care Guide
Introduction
The Black Arrow Royal Tetra (Inpaichthys sp. 'Black Arrow') is a stunning and likely undescribed species within the Inpaichthys genus, belonging to the Characidae family, a diverse group of small to medium-sized freshwater fish native to South America. This species is distinguished by its sleek, torpedo-shaped body and bold visual features. A prominent dark lateral stripe extends from just behind the pectoral fins to the base of the caudal fin, evoking the appearance of an arrow and likely inspiring its common name. Its refined body shape and vivid contrast make it a visually captivating addition to well-maintained aquaria.
The Black Arrow Royal Tetra is a shoaling species that thrives in the company of its own kind. To encourage natural behaviour and reduce stress, keep them in groups of six or more. These fish display coordinated swimming and increased confidence in a well-sized shoal, enhancing their vivid lateral markings. When kept in a group that is too small, they may become timid or inactive.
Peaceful by nature, the Black Arrow Royal Tetra is a perfect addition to your aquarium. It can be housed with various similarly sized and temperament-matched species, making it a versatile choice for your tank. Suitable tankmates include other small, peaceful tetras, dwarf cichlids (Apistogramma spp.), Corydoras catfish, and rasboras. Avoid aggressive or fin-nipping fish, such as larger barbs or some betta varieties, as these can cause stress or damage to the Tetra's delicate fins.
The Black Arrow Royal Tetra requires an aquarium that closely replicates the calm, shaded streams of its natural habitat in South America. A well-planted tank of at least 75 litres (20 gallons) is recommended, offering ample swimming space and visual barriers to promote natural shoaling behaviour. The aquascape should include a soft, dark substrate, driftwood, and dried leaf litter to create a blackwater effect that enhances the fish's colours and sense of security.
Subdued lighting, ideally filtered through floating plants, will mimic the dappled light of forested waters and help reduce stress. A gentle, reliable filtration system is essential to maintain water clarity without creating strong currents. Frequent water changes and a stable environment are key to ensuring long-term health and natural behaviour in this sensitive species.
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Sexual Dimorphism
Sexual dimorphism in Black Arrow Royal Tetras is subtle. Males are often slightly slimmer and may display more intense colouration, particularly during courtship. Females are generally fuller-bodied, especially when gravid. Behavioural observation during breeding is often the most reliable method for distinguishing the sexes.
Quick Facts
| Scientific Name | Inpaichthys sp. 'Black Arrow' |
|---|---|
| Other Names | Black Arrow Tetra |
| Kingdom | Animalia |
| Classification | Actinopterygii |
| Order | Characiformes |
| Family | Characidae |
| Genus | Inpaichthys |
| Origins | Brazil |
| Approx Max Size | 5 cm |
| Temperament | Peaceful |
| Aquarium Level | Middle |
| Difficulty | Beginner - Intermediate |
| Shoaling | Yes |
| Best kept as | Groups 6+ |
| Diet & Feeding | Omnivore |
| Reproduction | Egg-Scatterer |
| Average Lifespan | Up to 5 Years |
Water Parameters
| Water Type | Freshwater |
|---|---|
| pH | 6.0 - 7.0 |
| GH | 2 - 10 |
| ℉ | 72 - 79 |
|---|---|
| ℃ | 22 - 26 |
Natural Habitat
Though the exact distribution of Black Arrow Royal Tetras has not been formally documented, they can likely be found in the Rio Aripuana in the Brazilian state of Mato Grosso in South America. Members of the Inpaichthys genus are endemic to the Amazon Basin in South America, with known populations occurring in Brazil. They are typically found in clearwater or blackwater streams, often with dense submerged vegetation and shaded by forest canopy. These waters are characterised by their low mineral content, high tannin levels from decaying leaf litter, and reduced light penetration conditions that are important to replicate in captivity for optimal health and natural behaviour.
Breeding
Breeding Black Arrow Royal Tetras in captivity is possible but not commonly documented, likely due to its rarity. As with many Tetras, they are presumed to be egg scatterers, depositing eggs among fine-leaved plants or spawning mops. Soft, acidic water and a separate breeding tank with controlled lighting and stable temperature will increase the chances of success. Adults should be removed post-spawning to prevent egg predation. Eggs typically hatch within 24–48 hours, with fry requiring infusoria initially, followed by newly hatched brine shrimp.
Diet & Feeding
The Black Arrow Royal Tetra is an omnivorous micro-predator that feeds primarily on small aquatic invertebrates, insect larvae, and zooplankton in the wild. This species adapts well to a varied diet in captivity but benefits greatly from foods that mimic its natural feeding patterns. For optimal health, colouration, and vitality, offer a mix of high-quality micro pellets or fine granules as a staple diet. Enhance their diet with live or frozen foods like daphnia, brine shrimp, cyclops, and bloodworms, as these options promote natural foraging behaviour and support overall health and vitality. Flake foods may also be accepted, but should not be the sole food source, as they lack the protein variety these tetras thrive on.
Feeding should be done in small portions, 1 to 2 times daily, ensuring all food is consumed within a few minutes to evade excess waste and water quality issues. Their small mouths and preference for midwater feeding should be considered when choosing food size and type. A diverse and protein-rich diet is essential for conditioning fish for breeding.
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Published: 23 May 2025
Last Updated: 23 May 2025