Altum Angelfish Breeding Guide
Why Pterophyllum altum is rarely bred in captivity: extreme blackwater demands, wild-caught stock and general angelfish spawning behaviour.
Overview
Altum angelfish (Pterophyllum altum) is the largest Pterophyllum, from the Orinoco basin. True wild-caught Orinoco altum is very difficult to breed in captivity, and most specimens in the trade are wild-caught rather than captive-bred. The species is recommended for intermediate to advanced aquarists because of the detailed maintenance it requires.
Sexing
As with the genus generally, it is very difficult to accurately identify the sex of any Pterophyllum individual until it is nearly ready to breed, when the breeding tubes become visible.
Conditioning
Wild-caught fish are available only seasonally (typically late summer to early winter, reflecting July-October fishing in the native range). Acclimatising them to extreme blackwater conditions and stabilising a group is the prerequisite for any spawning attempt.
Breeding Setup
- Very transparent blackwater with almost nil conductivity
- pH approximately 4.5-5.8
- Temperature 26-29 °C (78-84 °F)
- Well-oxygenated, extremely soft water
- Submerged roots or branches in a moderate current as a spawning site
Spawning Behavior & Trigger
Unlike related angelfish that use plant leaves, P. altum prefers to spawn on submerged roots and tree branches in a moderate water current. In the genus, the pair cleans the chosen surface over a day or two; the female lays a line of eggs that the male then fertilises, and this repeats until the clutch is complete.
Egg & Fry Care
Pterophyllum show highly developed biparental brood care, fanning the eggs with their pectoral fins. Eggs hatch within a few days and the fry remain attached to the spawning substrate, becoming free-swimming after about a week, at which point they take suitably sized live food.
Common Challenges
Captive spawning of true altum is rare and unreliable, largely because reproducing the extremely soft, acidic, low-conductivity blackwater is demanding. Reliance on seasonal wild-caught stock and slow pair formation compound the difficulty.