Angelfish

About the species

The angelfish (Pterophyllum scalare) is a cichlid from the Amazon basin, with a body shape quite unlike round or elongated tankmates such as the guppy or neon tetra – its body is laterally compressed and grows considerably taller than it is long, which makes tank height, not just volume, the key factor when choosing an aquarium. Unlike calm shoaling fish, the angelfish is also a territorial cichlid In the wild, angelfish live among submerged roots and branches in slow-moving channels of the Amazon and Orinoco basins, where their vertical stripes and flattened body help them stay almost unnoticed among the vegetation.that can become considerably more assertive toward tankmates as it matures.

Aquarium: height matters, not just litres

A recommended base tank size for a small group of angelfish is roughly 100 × 40cm with a height of at least 50cm, equivalent to about 200 litres – this emphasis on height matters more for angelfish than for most other aquarium fish, since an adult's fins and body reach quite high. A tank that is too small or too shallow restricts natural vertical swimming and increases stress.

Water and maintaining quality

The angelfish needs warm water, between 24 and 30°C, noticeably warmer than the neon tetra, which tolerates the cooler end of its shared Amazonian origin. Recommended pH is between 6.0 and 7.4, with general hardness soft to moderate, roughly up to 15 °dH; for this species, stability of values matters more than hitting one exact number.

When an angelfish becomes a predator

Juvenile angelfish are relatively calm toward other small fish, but an adult may eventually treat sufficiently small tankmates, such as neon tetras or other tiny tetras, as food. This is not aggression in the general sense but natural predatory cichlid behaviour, and it is worth factoring in when planning a community tank from the start.

Pairing and territoriality

Angelfish form pairs that become strongly territorial during spawning and may aggressively defend part of the tank against other fish, including other angelfish. Because of this, a smaller tank with angelfish should hold either a single pair or a group large enough that aggression is spread across several individuals rather than focused on one.

Diet

The angelfish is omnivorous – in the wild it feeds on small invertebrates and plant material, and in the aquarium it readily accepts quality pellets and flakes, supplemented with live or frozen food such as mosquito larvae or brine shrimp. A varied diet supports colour development and fin shape.

Growth and development

An angelfish grows from a tiny fry into a cichlid with a fin span of around 15cm or more, a process that takes several months to a good year, which is why many keepers buy a group of juveniles and gradually rehome them as they grow and form pairs. Growth rate depends on water quality, diet and tank size.

Varieties and colour forms

Beyond the wild silver-and-black striped form, selective breeding has produced numerous colour variants, from nearly solid black to marbled, smoky or so-called koi patterns, as well as veil-finned varieties with much longer fins. Long fins look striking but are also more vulnerable to damage from fin-nipping tankmates or sharp decorations, which is worth considering when setting up the tank.

Who the angelfish suits

Because of its need for a tall tank, stable water parameters and carefully chosen tankmates, the angelfish suits aquarists with at least some experience better than a very first tank. Under the right conditions, it is one of the more recognisable and long-term rewarding species in hobby fishkeeping.

Pros & cons