Altum Angelfish Care Guide Freshwater: Pterophyllum Altum

Separate species, separate rules. The altum angelfish care guide freshwater below treats Pterophyllum altum as the Orinoco-specialist blackwater fish it is, not as a taller version of the standard scalare. At Gensou Aquascaping in Everton Park, Singapore we keep a dedicated altum display at pH 5.2 and 28 degC. Every aspect — tank height, water chemistry, diet, quarantine — has to match the soft acidic blackwaters of the Río Atabapo and Río Orinoco drainage if the fish are to thrive past the first six months.

Quick Facts

• Scientific name: Pterophyllum altum — distinct from P. scalare
• Origin: upper Orinoco basin, Colombia and Venezuela
• Adult size: 18 cm body length, 38-45 cm fin-to-fin height
• Minimum tank: 350 litres, 60 cm tall minimum; ideal 80 cm
• Water: pH 4.5-6.0, GH under 3, KH near zero, 27-30 degC
• Diet: live and frozen — bloodworms, black worms, daphnia, mysis
• Temperament: peaceful but fragile; keep in groups of five or more

Altum vs Scalare — Genuine Differences

The altum is taller, with a deeper notch above the eye and a more pronounced forehead indentation. More importantly, its physiology is tied to blackwater. Scalare will adapt to Singapore tap water within reason; altum will not. Misidentified juveniles are common in the trade, so buy only from a specialist and ask for collection locality. True altums usually enter Singapore via Colombian exporters and sell for $180-350 SGD each at sub-adult size.

Blackwater Chemistry

The defining care requirement is water. Pass RO through peat, catappa leaves, and alder cones to drop pH into the 4.5-6.0 range. KH should be effectively zero so pH holds naturally without buffering. GH under 3 degrees is non-negotiable — our Orinoco tank sits at GH 2, KH 0, pH 5.2, TDS 80-100. Singapore tap is too hard and too alkaline at source; plan on RO/DI production of at least 50 litres weekly for water changes.

Tank Height and Aquascape

Altums need vertical space. A 60 cm tall tank is workable for sub-adults; 70-80 cm is required for mature fish. Use tall hardscape — driftwood spires and branches — rather than low iwagumi layouts. Amazon sword, Echinodorus grisebachii, and floating Salvinia provide cover without crowding the swimming column. Dim lighting and a substrate of dark sand or ADA Amazonia give the blackwater mood these fish respond to.

Temperature, Flow, and Oxygen

Warm — 28-30 degC is their native range. Singapore ambient works without a heater, but evaporation from open-top tanks concentrates dissolved organics. Flow should be gentle; these are deep-flooded forest fish, not river species. Run an oversized canister at reduced flow through a spraybar, and keep surface agitation modest.

Diet and Feeding

Wild-caught altums often refuse dry food for weeks. Start with live black worms, live daphnia, and frozen bloodworms, transitioning to high-quality pellets such as Hikari Vibra Bites over one to two months. Three small meals a day beats one heavy feed. Never overfeed in blackwater — low KH means ammonia shifts hit hard.

Group Behaviour and Tank Mates

Altums are social, not solitary. A group of six allows natural pair formation and prevents bullying. Compatible tank mates include cardinal tetras, rummynose tetras, Apistogramma species, and Corydoras sterbai — all Orinoco-adjacent and tolerant of the same soft acidic conditions. Avoid any fin-nippers and any fish that require harder water.

Quarantine and Common Issues

Wild altums frequently carry capillaria, hexamita, and external flukes. A 30-45 day quarantine with praziquantel and metronidazole is standard. The number one killer of imported altums in the first month is water chemistry shock — never skip proper drip acclimation over four hours. Once settled in blackwater, altums are no more fragile than any other wild fish, often living 8-10 years.

Related Reading

• Angelfish Care Guide
• Blackwater Aquarium Setup Guide
• Discus Fish Care Guide
• Angelfish Colour Genetics Breeding Guide
• How to Breed Angelfish Complete Guide