Rio Negro Altum Angelfish (Pterophyllum altum)

The Rio Negro Altum Angelfish (Pterophyllum altum) is one of the most admired wild angelfish varieties in the aquarium hobby. Native to the Rio Negro River system in Brazil and Colombia, this population of Altum angelfish is prized for its impressive body height, elegant fins, and subtle reddish or copper tones that may appear on the fins and body under proper lighting.

Often referred to as the “King of Angelfish,” the Rio Negro Altum is known for its majestic appearance and graceful swimming behavior. Its extremely tall body and long flowing fins create a dramatic silhouette that makes it a stunning centerpiece fish for large freshwater aquariums.

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Natural Habitat

Rio Negro Altum Angelfish inhabit blackwater environments in the Rio Negro basin, one of the largest tributaries of the Amazon River. The water in this region is typically dark and tea-colored due to high levels of tannins released from decomposing leaves and wood.

Typical natural conditions include:

• Soft, mineral-poor water
• Very acidic pH levels
• Warm tropical temperatures
• Submerged roots and driftwood
• Dim lighting caused by tannin-stained water

These unique environmental conditions contribute to the distinctive appearance and behavior of Rio Negro Altum Angelfish.

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Physical Characteristics

Rio Negro Altum Angelfish are easily recognized by their dramatic body shape and elegant fins.

Key features include:

• Extremely tall body profile
• Long dorsal and anal fins
• Bold vertical black stripes across the body
• A noticeable notch or dip above the forehead, which distinguishes true Altum angelfish
• Subtle copper or reddish coloration on fins and body in some specimens

Average Adult Size

Length: 6–7 inches (15–18 cm)
Height: 10–12 inches (25–30 cm) including fins

This impressive height makes Altum angelfish the largest species of angelfish kept in aquariums.

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Behavior & Compatibility

Despite being a member of the cichlid family, Rio Negro Altum Angelfish are generally peaceful and calm when kept in appropriate environments. They tend to do best when kept in small groups or spacious aquariums.

Suitable tank mates may include:

• Larger peaceful tetras
• Corydoras catfish
• Peaceful dwarf cichlids
• Other calm South American species

Very small fish and shrimp may be seen as food.

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Ideal Aquarium Setup

Rio Negro Altum Angelfish require large aquariums with significant vertical height due to their tall body structure.

Recommended aquarium features:

• Tall aquariums with plenty of swimming space
• Driftwood and natural root structures
• Blackwater botanicals such as Indian almond leaves
• Gentle water movement
• Dim or subdued lighting

Replicating a natural blackwater environment will help these fish feel comfortable and display their best coloration.

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Diet and Feeding

Rio Negro Altum Angelfish are omnivorous with a preference for protein-rich foods.

Recommended foods include:

• High-quality pellets
• Frozen bloodworms
• Brine shrimp
• Daphnia
• Occasional live foods

Providing a varied diet helps maintain their health, growth, and coloration.

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Recommended Tank Parameters

Temperature: 80 – 86°F (27 – 30°C)
pH: 4.8 – 6.5
KH: 0 – 2 dKH
Minimum Tank Size: 75 gallons or larger

Stable water conditions are very important for this species.

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Origin

The Rio Negro Altum Angelfish originates from the Rio Negro River basin in Brazil and Colombia, one of the most famous blackwater ecosystems in the Amazon region. Most specimens available in the aquarium trade are wild-caught, which makes them highly valued among experienced aquarists.