Altum Angelfish

Geographical Origin & Biotope:

*Pterophyllum altum* is strictly endemic to river basins in northern South America, specifically the entire Orinoco River system (between Colombia and Venezuela) and the upper Rio Negro basin in Brazil (a gigantic blackwater tributary of the Amazon River). Its primary biotope consists of extreme blackwater or clear but amber-tinted waters, characterized by a frightening amount of submerged wood, hanging roots, decaying leaves, and very little true aquatic vegetation, with dim, penetrating light.

Taxonomy & Morphology:

An iconic member of the Cichlidae family, the Altum is clearly distinguished from other *Pterophyllum* by a key morphological detail: a deep indentation (the so-called "notch" or "saddle") on the forehead, just above the snout, giving it an almost snub-nosed profile. It is a vertical giant: its dorsal and anal fins extend upward and downward like immense sails of a galleon, making it the tallest cichlid in the world in proportion to its length (up to 35-40 cm / 14-16 inches in total height against 18 cm / 7 inches of body length).

Social Behavior:

In the wild, it lives in immense schools that glide through the tangled roots in a coordinated and silent manner, protecting each other from predators (like large piscivorous cichlids and Piranhas). In the aquarium, they must strictly be kept in groups of no less than 5 or 6 specimens to diffuse hierarchies and intraspecific aggression. Hierarchies are established through ritualized displays, where they face off by expanding their gills and flaring their fins, but true physical clashes are very rare outside the breeding season.

Coloration & Sexual Dimorphism:

The Altum's base livery is a spectacular silver, sometimes infused with slight purplish, coppery, or golden reflections depending on the lighting and mood. It is crossed vertically by three or four massive, deep black bands: one passing through the eye, a massive central one, and one on the caudal peduncle. Unlike domestic Angelfish, there are no (and should not be) selected or hybrid color varieties. Sexual dimorphism is impossible to determine with the naked eye until the pair is spawning, at which point the female extrudes a thicker ovipositor.

Tank Setup:

Vertical dimension is the most critical factor in keeping *Pterophyllum altum*. A healthy adult can develop spectacular dorsal and anal fins that push the fish's total height beyond 35 centimeters (14 inches). Consequently, the net water column must never be less than 60 cm (24 inches), making aquariums 70-80 cm deep and with volumes of 400+ liters (100+ gallons) ideal for a small school. The perfect layout emulates the flooded banks of the Orinoco: fine light sand substrate, a tangle of thick roots arranged vertically (resembling submerged branches), and an abundance of Indian Almond leaves on the bottom.

Diet & Feeding:

In the wild, they are patient predators that feed on macroinvertebrates, shrimp, and small fish among the submerged branches. In the aquarium, wild-caught specimens are notoriously difficult to wean and may require exclusively live foods for the first few months. Gradually, they will accept frozen bloodworms, mysis, adult brine shrimp, krill, and eventually, super-premium high-protein sinking pellets. Being voracious and susceptible to intestinal parasites, supplementing their food with garlic or vitamin extracts is excellent prophylaxis.

Water Quality:

The Altum does not compromise. The water must be pristine, extremely soft (GH 1-5, carbonate hardness near zero), and acidic (pH 4.5 - 6.5). Originating from torrid climates, it requires consistently high temperatures between 28°C and 32°C (82-90°F). The filtration system must be oversized to handle biological waste without creating swirling currents. Blackwater peat filtration and frequent water changes (even 30-40% weekly) using exclusively remineralized reverse osmosis water are mandatory to guarantee their long-term survival.

Compatibility & Tankmates:

Compared to the common Angelfish, the Altum is more majestic but also more timid and psychologically delicate. It scares easily and must never share the tank with hyperactive, fin-nipping, or aggressive fish. Ideal tankmates are Symphysodon (Discus), which share the same extreme requirements for temperature and soft water. For the bottom, you can add schools of Corydoras sterbai (the only ones that tolerate high temperatures well) and Loricariids. Inevitably, the Altum will prey on torpedo-shaped fish like Neon Tetras.

Aquarium Breeding:

Captive breeding is extremely rare and considered a crowning achievement in an aquarist's career. It follows the classic methodology of large South American cichlids: a monogamous pair detaches from the group, meticulously cleans a smooth vertical surface (a trunk or the filter wall), and deposits hundreds of eggs. Reproductive success requires extreme parameters: pH around 5.0 or lower and almost zero conductivity, so that the sperm remain motile and the eggs do not calcify.

Risks & Diseases:

The Altum has a weak immune system against common pathogens in community aquariums and is highly susceptible to two scourges: Hexamita (the infamous hole-in-the-head disease, driven by stress or dietary deficiencies) and intestinal nematodes (Capillaria). Stressed specimens will exhibit stringy white feces and emaciation, even while continuing to eat. Ich can hit them hard if temperatures suddenly drop below 27°C (80°F).