F1 Rio Atabapo Altum

Altum Angelfish (Pterophyllum altum)

A majestic and highly sought-after angelfish from the soft, acidic blackwaters of the Upper Orinoco and Negro River systems in South America. Larger and more demanding than the common angelfish (Pterophyllum scalare), the Altum is renowned for its dramatically tall, sail-like fins that can reach nearly 20 cm in height, giving it an elegant, almost regal presence. Named for its impressive dorsal fin (from the Greek pteron for “fin/sail” and phyllon for “leaf”), this species is a true centerpiece for advanced aquarists with the right setup.

Key Features

• Maximum Size: 18 cm / ~7 inches TL; height up to ~20 cm with fully developed fins.
• Appearance: Tall, laterally compressed body with exceptionally elongated dorsal and anal fins. Coloration is typically silvery with subtle vertical banding and a slight iridescent sheen; intensity varies with mood, lighting, and water quality. Males and females are similar, though males may develop a more pronounced nuchal hump with age.
• Fin Details: Extremely tall, sail-like dorsal and anal fins; the genus name directly references this striking fin structure.

Aquarium Care

• Tank Size: Minimum 75–125 gallons for a small group (larger is strongly recommended due to adult size and fin span).
• Water Parameters: Soft, acidic tropical freshwater; 80–88°F (27–31°C), pH 4.8–6.2, very low hardness (1–5°dGH). Excellent water quality with frequent partial changes is critical. Use RO or rainwater remineralized appropriately, with tannins from driftwood or Indian almond leaves to maintain low pH. Provide tall plants, driftwood, and vertical structures for cover while leaving open swimming space.
• Diet: Omnivorous — accepts high-quality flakes, pellets, frozen foods (bloodworm, brine shrimp, beef heart mixes), and occasional live foods. A varied diet supports health and fin development.
• Behavior: Generally peaceful when kept in groups but can be territorial toward other angelfish or similar-shaped fish. Best kept as a small group (6+) to spread aggression and encourage natural behavior. Sensitive to poor water conditions and sudden parameter changes; wild-caught specimens are particularly delicate. Breeding is challenging and requires pristine conditions.

IUCN Status Least Concern (LC)

Add majestic height, elegant presence, and sophisticated blackwater beauty to your advanced aquarium with the spectacular Altum Angelfish!

Pictured is the wild parent, an ACA award winner!

Selling Size: Half Dollar Body