Bloodfin Tetra

Aphyocharax anisitsi, the Bloodfin Tetra, is native to the Río Paraná basin in Argentina, where it inhabits fast-flowing, cool, well-oxygenated rivers and streams. Its most striking feature is the dramatic contrast between its glassy silver body and the deep blood-red coloration of all fins — dorsal, anal, pelvic, and caudal — giving it an unmistakable appearance in the aquarium. One of the Bloodfin Tetra's most notable qualities is its cold tolerance; it can thrive at temperatures as low as 18°C, making it suitable for unheated aquariums in temperate climates or for aquarists who prefer cooler water setups. Despite this cold adaptability, it also does well at typical tropical temperatures. The Bloodfin is an extremely active, fast-moving schooling fish that spends most of its time in the middle water column. It is entirely peaceful and reliable with tankmates of all sizes, though it may nip the fins of very slow, long-finned species when kept in small groups. Keeping large schools of 10 or more is ideal and eliminates any minor schooling aggression by directing the fish's attention toward conspecifics. The Bloodfin Tetra is one of the easiest tetras to keep and is an excellent recommendation for new aquarists.

Tank Setup A 60-liter aquarium suits a school comfortably. This active fish needs horizontal swimming space, so long, shallow tank profiles are preferred over tall ones. Plants along the sides and back create visual interest while preserving a central swimming corridor. Good surface agitation provides oxygenation this species appreciates.

Water Parameters Maintain pH 6.0–7.5, temperature 18–25°C. One of the few tetras capable of thriving in unheated aquariums in temperate rooms. Water hardness is flexible. Perform 25% weekly water changes. Ensure strong oxygenation, especially at warmer temperatures.

Filtration This species prefers moderately flowing water compared to many tetras. A canister filter providing some current, or an internal filter with directed flow, suits it well. Good biological filtration is important for long-term water quality.

Diet Feed quality flake food, micro-pellets, and frozen or freeze-dried brine shrimp, daphnia, and bloodworms. This species is not fussy and will accept most foods. Feed twice daily. Varied diet maintains robust health and fin color.

Tankmates Peaceful with virtually all community fish of appropriate size. Compatible with other tetras, barbs, danios, rasboras, corydoras, and small loaches. Avoid very slow or long-finned species in small groups. Well-suited to cold-water community tanks with white cloud mountain minnows or similar species.

Breeding Egg scatterers that spawn over fine-leafed plants. Use a separate breeding tank with soft, slightly acidic water and dim lighting. Condition with live foods. Parents eat eggs; remove after spawning. Fry hatch in 24–36 hours and become free-swimming quickly. Feed baby brine shrimp.