Rathbun's Bloodfin (Aphyocharax rathbuni) — 2,5-3,5cm

Overview

The Rathbun's Bloodfin (Aphyocharax rathbuni) is a small, peaceful schooling tetra for sale UK that showcases brilliant blood-red fin coloration and lively movement in planted community aquariums. Native to the Amazon basin in Brazil, this attractive tetra forms tight schools that create synchronized swimming displays reminiscent of natural blackwater streams. With its modest size, peaceful temperament, and striking red fin flash, Rathbun's Bloodfin makes an excellent addition to South American community aquariums with similarly sized peaceful species. Proper schooling and planted aquascapes bring out the best in this charming species, rewarding fishkeepers with vibrant color and engaging behavior.

Appearance

Aphyocharax rathbuni presents a compact, streamlined body with translucent silvery coloration that allows visibility of the lateral line and internal structures. The defining feature is the brilliant blood-red to orange-red coloration on all fins, creating spectacular flashes of color when the school moves in unison. The intensity of red fin coloration varies with diet, water conditions, and individual health—well-maintained specimens display particularly vivid hues. The body itself shows subtle iridescence under appropriate lighting. Eyes are proportionally large and dark. Sexual dimorphism is subtle; males are typically slightly slimmer with more intense fin coloration, particularly when in breeding condition. The overall effect is elegant simplicity—a silver body accented by brilliant red fins.

Natural Habitat

This species inhabits slow-moving streams, tributaries, and flooded forest areas in the Amazon basin of Brazil, though detailed locality information remains limited. In nature, Rathbun's Bloodfin forms schools in areas with dense aquatic vegetation, submerged roots, and leaf litter. The water is typically soft, slightly acidic, and stained with tannins from decomposing organic matter, creating the characteristic blackwater or clearwater conditions of Amazonian habitats. These tetras occupy the mid-water column, feeding on small invertebrates, insect larvae, and zooplankton. The complex vegetation structure provides both foraging opportunities and refuge from predatory fish.

Aquarium Setup

A minimum 75-litre aquarium provides adequate space for a proper school of 8-10 individuals with room for additional community species. Create a South American biotope using fine sand or small gravel substrate, driftwood arranged to create visual interest, and generous planting with a mix of background, midground, and some floating plants. Maintain areas of dense vegetation balanced with open swimming space through the center where the school can display natural behavior. Lighting should be subdued to moderate—floating plants help diffuse intense light. Filtration should provide gentle water movement without creating strong current. A secure lid is essential, as these tetras are capable jumpers when startled or during evening hours. Include Indian almond leaves, alder cones, or peat filtration to release beneficial tannins that replicate natural conditions and enhance fish coloration.

Water Parameters

Maintain soft to neutral water conditions typical of South American blackwater habitats. Target pH of 6.0-7.5, with soft water below 10 dGH ideal, though this species adapts to moderate hardness. Temperature should remain stable at 24-27°C using a reliable heater and accurate thermometer. Water quality must be excellent: ammonia and nitrite always zero, nitrates below 20 ppm through regular 25-30% weekly water changes. Use dechlorinated water, ideally softened with reverse osmosis, rainwater, or deionization if tap water is hard. Stability is more important than hitting exact parameters—avoid sudden shifts. Consider using natural tannin sources like Indian almond leaves, alder cones, or commercial blackwater extracts to create the slightly acidic, tannin-rich water that enhances coloration and replicates natural habitat. Test regularly and maintain consistent conditions.

Feeding

Offer a varied omnivorous diet including high-quality micro pellets or finely crushed flakes as a staple, supplemented regularly with small frozen or live foods such as daphnia, baby brine shrimp, bloodworms, and cyclops. Include some plant-based matter or spirulina-enriched foods for balanced nutrition. Feed two to three times daily in small portions that can be consumed within 2-3 minutes. This species is an enthusiastic feeder that responds particularly well to live foods, which trigger natural foraging behavior and help condition fish for breeding. Variety is essential for maintaining vibrant red fin coloration—carotenoid-rich foods enhance red pigmentation. Observe feeding to ensure all fish receive adequate nutrition. Well-fed schools display more confident behavior and intensified coloration. Newly hatched brine shrimp are excellent for conditioning breeding groups.

Behaviour

Rathbun's Bloodfin displays peaceful schooling behaviour characteristic of small South American tetras. In proper schools, they form tight, coordinated groups that move in graceful synchronization through planted aquascapes. The species is active throughout the day, constantly exploring the mid-water column and foraging for food. Schooling behavior intensifies when the group feels secure—well-planted tanks with subdued lighting and tannin-stained water encourage confident, natural behavior. Individual fish kept in too-small groups become stressed, shy, and lose color intensity. In appropriately sized schools with peaceful tankmates, this species creates dynamic movement patterns that showcase their brilliant red fins. Most active during daylight hours, with increased activity around feeding times. Provide ample swimming space balanced with planted refuge areas to accommodate their active nature.

Tank Mates

Ideal tank mates include small peaceful tetras, rasboras, small Corydoras catfish, Otocinclus, and peaceful livebearers of similar size. Other peaceful South American species make natural companions in biotope setups. Avoid housing with large predatory fish that will view them as food, fin-nipping species that will damage their colorful fins, very aggressive cichlids, large barbs, and fish large enough to eat them. Timid, slow-moving species may be outcompeted at feeding time. The key is selecting peaceful, active community fish of similar size and temperament. In well-balanced communities with proper group sizes for all schooling species, Rathbun's Bloodfin coexists peacefully and contributes vibrant color and movement to the aquarium. Particularly effective in planted South American community aquariums with diverse small peaceful species.

Breeding

Spawning is typically by egg scattering among fine-leaved plants or spawning mops in soft, slightly acidic water. To encourage breeding, set up a separate breeding tank (40-60 litres) with soft water (pH 6.0-6.5), subdued lighting, fine-leaved plants like Java moss or spawning mops, and gentle sponge filtration. Condition a group of adults with high-quality live and frozen foods until females become visibly rounded with eggs. Introduce one or two pairs in the evening. Spawning typically occurs at dawn, with eggs scattered among plants. Adults show no parental care and will consume eggs—remove adults immediately after spawning. Eggs hatch in approximately 24-36 hours depending on temperature. Fry become free-swimming 3-4 days after hatching and require microscopic foods like infusoria or liquid fry food initially, graduating to newly hatched brine shrimp within one week. Maintain pristine water quality during fry-rearing with gentle filtration and small frequent water changes. Fry grow slowly initially but develop characteristic red fin coloration within 6-8 weeks.

Why Buy from Tropical Fish Co

Tropical Fish Co specializes in premium South American tetras, including the beautiful Rathbun's Bloodfin. Every fish undergoes comprehensive quarantine in conditions replicating natural habitat parameters and thorough health screening before dispatch. Our expert team provides detailed guidance on schooling fish care, planted aquarium design, and South American community stocking to ensure your success. We offer secure next-day delivery throughout the UK with professional insulated packaging and seasonal temperature control. Our commitment includes healthy, vibrant fish showing excellent coloration, backed by our live arrival guarantee and ongoing support for the life of your aquarium. Whether establishing your first planted community or expanding an existing South American biotope, trust Tropical Fish Co for exceptional quality, expert knowledge, and customer service that stands behind every fish. Bring the vivid colors of the Amazon basin into your home with confidence.