Angelfish Size: How Big Do They Get?
Understand the full growth potential of freshwater angelfish, including their significant height, and what it takes to raise them to a healthy adult size.
Freshwater angelfish are a popular aquarium fish, easily recognized by their compressed, triangular bodies and long, flowing fins. Native to the slow-moving waters of South America, these fish have captivated keepers with their graceful swimming behavior. Many different color varieties have been developed from the wild, silvery form that has four black vertical stripes.
Expected Adult Size
When considering the adult size of the common freshwater angelfish, Pterophyllum scalare, it is important to think about two different measurements: length and height. An adult angelfish can reach a body length of up to 6 inches (15 cm) from its mouth to the base of its tail. However, their height, which includes their prominent dorsal and anal fins, can be significantly greater, often reaching 8 inches (20 cm) or more.
Aquarists often purchase angelfish as small juveniles, sometimes only the size of a coin, which can create a misleading expectation of their ultimate size. The altum angelfish (Pterophyllum altum), a less common species, grows even larger, reaching heights of 10 to 13 inches (25-33 cm).
Growth Rate and Timeline
The most significant growth spurt occurs within the first six months of their life. During this time, a young angelfish can expand from less than an inch to about four inches in height, at which point they are considered adults. Following this initial rapid phase, the growth rate slows considerably.
It can take another six months to a year, or sometimes slightly longer, for an angelfish to reach its maximum potential size. Most angelfish will reach sexual maturity and be capable of breeding between eight to twelve months of age. The process to reach their full adult dimensions takes about one to one and a half years.
Key Factors for Proper Growth
Several factors influence whether an angelfish will reach its full size potential. A high-quality, protein-rich diet is necessary for healthy development. In their natural habitat, angelfish consume small crustaceans and invertebrates, so replicating this with varied commercial foods and frozen options like brine shrimp or bloodworms supports proper growth.
Water quality plays a direct role in an angelfish’s development. These fish are intolerant of ammonia and nitrite, and high levels of nitrates can cause stress that diverts energy from growth. Frequent water changes are encouraged to maintain clean water parameters, with a pH between 6.0 and 7.5 and temperatures from 76 to 86°F (24 to 30°C).
Genetics set the blueprint for an angelfish’s potential size, as selective breeding has developed strains with different growth potentials. Tank space is another consideration, as insufficient room can lead to stunting, a condition where a fish’s growth is permanently limited.
Minimum Tank Size and Shape
The unique body shape of the angelfish directly influences its housing requirements. Because of their significant vertical height, the shape of the aquarium is just as important as its total water volume. A tall aquarium is necessary to comfortably accommodate the long fins of an adult angelfish, which can be 8 inches or more. A tank that is too shallow will not allow them to fully extend their fins.
For a pair of adult Pterophyllum scalare, a 30-gallon aquarium is a recommended minimum, with taller “high” or “show” tank configurations being preferable. For a small group of four to six juvenile angelfish, it is best to start with a larger tank to accommodate their growth. A tank height of at least 20 inches (50 cm) is advisable for adult fish to ensure they have adequate vertical space.