Keyhole Angelfish (Pterophyllum leopoldi)

Pterophyllum leopoldi is the smallest of the three recognized wild Pterophyllum species (alongside P. scalare and P. altum), reaching only 7–9 cm body length. Native to the upper Amazon River system in Brazil and the Essequibo River in Guyana, it inhabits slow-moving, heavily vegetated water with soft, acidic conditions — typically flooded forest margins, oxbow lakes, and vegetated river banks.

Distinguished from P. scalare by its more compact, rounded body with a shorter snout, and from P. altum by its smaller size and different body proportions, P. leopoldi features a distinctive large dark spot centered on the body (the 'keyhole' or 'teardrop' mark) along with vertical dark banding typical of the genus. The overall silver body with the characteristic tall, sail-like dorsal and ventral fin extensions gives the angelfish silhouette immediately recognizable to aquarists.

In the wild, P. leopoldi forms loose aggregations in slow-moving waters and feeds on small invertebrates, insect larvae, and organic particles drifting in the water column. Like other angelfish, it is a substrate spawner that deposits eggs on broad flat leaves, broad plant blades, or flat vertical surfaces.

P. leopoldi is rarer in the trade than common angelfish (P. scalare) and commands more attention from cichlid specialists and wild-type angelfish enthusiasts. Its smaller size relative to P. scalare makes it accessible for smaller aquariums.

Keyhole Angelfish require soft, warm, slightly acidic water: pH 5.5–7.0, hardness 1–8 dGH, and temperatures 26–30°C. As a wild-type species, it is more sensitive to water conditions than the highly adaptable commercially bred P. scalare strains.

A minimum 150-liter tall aquarium is recommended for a pair or small group — tall tanks suit the tall-bodied angelfish form. Provide tall, robust plants (Vallisneria, Amazon sword, broad-leaved Echinodorus), flat broad leaves or smooth slate pieces for spawning, and driftwood for cover. Dense plantings around the perimeter with open central space.

Feed a varied diet of quality flake food, medium pellets, and regular live or frozen supplements: bloodworms, brine shrimp, daphnia, and small earthworms. Angelfish are enthusiastic feeders that will readily accept most foods.

P. leopoldi can be kept with most peaceful community species that tolerate warm, soft water: small to medium tetras, corydoras, small catfish, and peaceful loaches. Avoid nippy species that target long fins (tiger barbs, serpae tetras), very small fish that may be consumed, or aggressive cichlids.

During breeding, pairs become territorial and will drive away tankmates from the spawning area. Regular water changes of 25–30% weekly maintain the conditions this demanding species requires.