The angelfish, also popularly known as the scalar fish, is undoubtedly one of the jewels of freshwater aquariums. Its elegant silhouette, marked by long fins and a disc-shaped body, along with the incredible diversity of colors and patterns, has made it an undisputed favorite for aquarists of all levels.
Native to the Amazon basin in South America, these fish not only bring beauty but also fascinating behavior. However, for them to thrive and display their full splendor, it is crucial to understand their specific needs.
In this AquaHoy guide, we will take you step-by-step through everything you need to know. From how to set up the ideal aquarium and clarify doubts about its size, to a complete guide on fish compatibility, their diet, the spectacular varieties that exist, and the secrets to achieving successful breeding.
Angelfish taxonomy
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Cichliformes
- Family: Cichlidae
- Tribe: Heroini
- Genus: Pterophyllum
- Species: Pterophyllum altum (the largest), Pterophyllum leopoldi (the rarest), and Pterophyllum scalare (the most common)
- Common Spanish names: Pez ángel, Pez escalar
- English names: angelfish, angel fish.
Madireddy (2022) represented the first de novo sequencing and assembly of the complete genome of the freshwater angelfish (Pterophyllum scalare); the final genome assembly consisted of 15,486 contigs.
Characteristics and types of Angelfish
Angelfish are a cichlid species native to the Amazon River system, which is why they can be found in several South American countries such as Colombia, Guyana, French Guiana, Peru, and Brazil.
The unique appearance of the angelfish comes from its long fins that make it incomparable when compared to other ornamental fish.
On the other hand, it is difficult to differentiate male angelfish from females. The physical differences that can be used to distinguish the sexes are often only visible during spawning.
Angelfish are also characterized by their longevity; when compared to other ornamental fish, they can live for up to 12 years.
The three species of angelfish are P. scalare, P. altum, and P. leopoldi; however, the most common and commercially traded in aquarium stores is P. scalare.
Pterophyllum scalare
The common angelfish. It is the most widespread in the hobby, with countless varieties developed through selective breeding. The P. scalare angelfish can reach a body length of 15 cm and a height (including fins) of 20 cm.
Pterophyllum altum
The altum angelfish. It is larger, with a taller body and a distinctive notch above its snout. It is more demanding regarding water quality and is considered a challenge for advanced aquarists. P. altum can grow up to 18 cm in length and 25 to 33 cm in height.
Pterophyllum leopoldi
The smallest and most aggressive of the three, recognizable by a black spot at the base of the dorsal fin.
Popular angelfish varieties
Angelfish breeders are continuously developing new angelfish colors and patterns, but the best-known varieties include silver, veil, koi, zebra, marble, albino, leopard, and platinum. Likewise, a transgenic angelfish has also been developed. Below is a brief description of each variety:
- Silver: The closest to the wild form, with vertical black bars.
- Marble: Irregular patterns of black and white (or gold).
- Black: An almost complete velvety black color.
- Koi: Orange, black, and white spots, reminiscent of koi carp.
- Zebra: Similar to silver but with more black stripes.
- Albino: Without pigmentation, with red eyes.
- Veil: With extremely long and flowing dorsal, anal, and caudal fins.
- Ghost: A fish with almost no stripes, very pale.
Angelfish reproduction
Angelfish reproduction is a spectacle. They are devoted parents who care for their spawn.
Reproduction genetics
The results of the study by Chu et al. (2025) demonstrate that the dnd1 gene is essential for fertility and plays a crucial role in promoting the female sexual fate in the freshwater angelfish (Pterophyllum scalare).
Pair formation
The ideal is to let a pair form naturally from a group of juveniles. You will know you have a pair when they isolate themselves from the group and defend a territory. Differentiating males from females is difficult, but in adults, the male usually has a small nuchal hump on its head and its ovipositor tube is pointed, while the female’s is more rounded.
Depending on aquarium conditions, P. scalare reaches sexual maturity between six and twelve months. For angelfish reproduction, you should choose a male and a female and place them in their tank for spawning.
On the other hand, Luna-Figueroa and Arce (2023) highlight that providing live food before and during the reproductive stage results in more intense and brilliant coloration, better condition, immunological strength, more active swimming, more numerous and frequent spawns, and a larger number of fry.
Spawning
Usually, three to four hours before reproduction, the male and female scalar fish clean, using their mouths, the substrate where they will lay the eggs (Thilakarathne et al., 2021). The pair will clean a smooth surface (a broad leaf, a log, or a breeding cone) and the female will deposit rows of angelfish eggs, which the male will immediately fertilize.
The female angelfish can lay hundreds of eggs every one or two weeks if the eggs are removed from the tank. A successful spawn can produce up to 1000 eggs. The eggs are generally deposited on vertical surfaces such as a leaf, the filter tube, or a section of the aquarium wall. Sihombing and Sitanggang (2021) evaluated different types of substrate and concluded that the ceramic substrate is the best for the scalar fish to deposit their eggs.
Care of the spawn
Both parents will fan the eggs with their fins to oxygenate them and will remove any that are not viable (those that turn white). Depending on the tank’s water temperature, the eggs will hatch in two to three days.
Care of the fry
After hatching, the fry will remain attached to the surface, feeding on their yolk sac. After 5-7 days, they will begin to swim freely. This is the time to feed them with infusoria or newly hatched brine shrimp. Eiras et al. (2019) report that angelfish larvae can be raised in salinities of up to 4 g/L NaCl, and that the best growth occurs at 2 g/L NaCl, with a feeding frequency of 4 times per day.
Transporting juveniles
One of the most important activities is the transfer of angelfish from hatcheries to ornamental stores or the aquarist’s home; in this regard, you can use eugenol at a concentration of 15.9 mg/L to transport the fish for a period of 7 hours (de Oliveira et al., 2019).
For their part, de Oliveira et al. (2022) evaluated the effects of the essential oils of Lippia sidoides (EOLS) and Cymbopogon citratus (EOCC), concluding that the best concentrations for sedation and anesthesia for the angelfish (Pterophyllum scalare) for both essential oils were 10 and 25 mg L−1.
Feeding scalar fish
Freshwater angelfish are easy to feed and will take all types of fish food because they are omnivores. In nature, they feed on small crustaceans, insects, and plant matter. For vibrant health, their diet must be varied.
- Base food: High-quality flakes or pellets for cichlids.
- Live or frozen food: Essential for their development and to encourage reproduction. Options like artemia, mosquito larvae, daphnia, or tubifex are excellent. Luna-Figueroa and Arce (2023) cite that Artemia franciscana nauplii, Moina wierzejski, and Panagrellus redivivus showed the highest daily and specific growth rates in angelfish larvae and juveniles, respectively; however, Oktavia and Firmani (2024) found that the use of Daphnia sp. as an exclusive natural food is superior to artificial pellets and other combinations of natural food for the growth and survival of manfish (P. scalare).
- Vegetable supplement: You can supplement with spirulina or homemade mashes that include peas or spinach.
The question “what do angelfish eat?” is answered with one word: variety. Feed them in small amounts twice a day.
Feed additives
The results of the research by Lima et al. (2024) demonstrated the potential of dietary supplementation with 0.2% β-glucans to improve the condition factor and positively modulate the intestinal microbiota of juvenile angelfish (P. scalare), without affecting other performance or blood parameters.
Feeding larvae and fry
For fry, Artemia nauplii are the best option to ensure rapid growth and higher survival. Likewise, Aziz et al. (2023) recommend feeding angelfish larvae with Artemia that has been enriched with microalgae (Tetraselmis sp. + Chlorella sp.); while Corecha et al. (2023) recommend the use of 75% Artemia franciscana nauplii and 25% Moina minuta neonates to reduce the feeding costs of angelfish larvae; and Eiras et al. (2022) report a feeding rate of 400 Moina sp. per postlarva/day, divided into two portions per day.
In the case of Pterophyllum scalare juveniles, Mao et al. (2023) recommend supplementing the commercial diet with 0.1% Artemia to improve the survival and growth of the fish, with a higher relative weight rate, standard length, and total length than the control group.
Feeding adult angelfish
In pet stores, you can find a variety of foods for your adult scalar fish; however, below we want to describe some research that can complement, and therefore improve, the nutrition of your angelfish.
Hamed et al. (2018) recommend the use of summer savory (Satureja hortensis) oil at an inclusion level of 200 mg/kg of feed to supplement the diet of angelfish, in order to improve growth, stress resistance, and the fish’s immune response.
Likewise, if you wish to enhance the coloration of your scalar fish, you can add 3% spirulina meal to the commercial feed, improving the color by a value of 3 (Lili et al., 2021).
Care of the Scalar fish
Angelfish can be kept in a wide variety of aquarium types, such as community and planted tanks; however, due to their height, angelfish need tall tanks. An adult angelfish requires space to swim vertically without its fins being damaged.
- Absolute minimum for a pair: 120 liters, but a 200-liter aquarium is strongly recommended for a small group of 4-5 young specimens, allowing them to establish their hierarchy and form pairs naturally.
- Height: The aquarium must be at least 50 cm tall.
- General rule: Calculate about 40-50 liters of water for each adult angelfish.
In Table 01, we present the range that the main water quality parameters in your aquarium must meet in order to raise angelfish without any problems.
Table 01. Technical sheet for raising angelfish.
| Parámetro | Rango |
| Volumen de la pecera | 200 litros para 4 adultos |
| Temperatura del agua | 25 a 28 oC. |
| pH | 6.0 – 8.0 |
| Dureza del agua | 3 y 8o dKH (54 a 145 ppm) |
Angelfish can be raised in a temperature range of 27 to 28 °C; however, Alvarez-Lee et al. (2023) suggest that an intermediate temperature of 28 °C should be used in production systems, as this condition represents the optimal physiology for the freshwater angelfish, and where the animals showed satisfactory performance.
Filtration and decoration
They prefer water with low current. An external or hang-on-back filter with regulated flow is ideal. Provide them with a fine and sandy substrate, and decorate with vertical driftwood and tall, broad-leaved plants like the Amazon Sword (Echinodorus), Vallisneria, or Anubias. These plants not only offer them security but are also the preferred place for them to deposit their eggs.
Angelfish behavior and compatibility
Generally, scalar fish are considered “semi-aggressive” because they chase each other in the aquarium. However, this territorial behavior occurs during the breeding season. dos Santos et al. (2018) conducted an experiment on the social interaction of angelfish and discovered that the increase in aggression is associated with the water change level; in this regard, the researchers recommend changing small volumes of water to prevent aggression and thus reduce the probability of injuries, stress, and affecting the fish’s well-being.
Environmental changes can affect some behavioral patterns in fish; in this sense, Ribeiro et al. (2021) evaluated the effects of water temperature on the aggressive behavior of male P. scalare, concluding that at low (23.8 °C) and high (31.7 °C) temperatures, there was a reduction in aggressive displays.
Fish compatible with scalars
The key is to choose tank mates of a similar size that are peaceful and not fin-nippers.
- Medium-sized Tetras: Neon tetras (if introduced when the angelfish are young), cardinal tetras, bleeding heart tetras, or serpae tetras. They should be kept in schools of at least 8-10 individuals.
- Corydoras and Ancistrus: Excellent bottom dwellers that will not compete for space. Keep them in groups of 6 or more.
- Dwarf Cichlids: The Ramirezi (Mikrogeophagus ramirezi) or the Kribensis Cichlid can be good companions in large aquariums with enough space and hiding spots.
- Loricariids: Moderately sized Plecos like Ancistrus are a great addition.
Warning! Species to avoid and risky combinations
- Very small fish: Guppies, small neons, or galaxy rasboras can be devoured by adult angelfish.
- Fin-nippers: Fish like the tiger barb or Buenos Aires tetra are a terrible choice, as they will harass the angelfish and damage their long fins.
- Gouramis: Although some guides list them as compatible, we advise against this mix. Both can be territorial and have similar body shapes, which often leads to conflict.
- Goldfish: They have completely different temperature and water requirements and should not be mixed.
Diseases of angelfish
Several common freshwater diseases affect angelfish in captivity:
Ich
White spot disease is caused by stress, which usually results from poor water conditions in the aquarium. The protozoan parasite Ichthyophthirius multifiliis causes white spots that attach to the fish’s body.
Ich can be treated by quarantining the affected fish in an aquarium where you should increase the water temperature to 30 °C with 1% salt (Abdullah-Al et al., 2021).
Dropsy
Dropsy is a symptom of an underlying bacterial infection, which can occur if the fish’s immune system is compromised.
This bacterial infection causes a bloated appearance, scales protruding from the body, bulging eyes, rapid breathing, lethargy, and loss of appetite.
You can treat dropsy with antibacterial medications recommended by a veterinarian, and add ⅛ of a teaspoon of salt for every five gallons of water.
Fin Rot
Fin rot is a bacterial infection that is commonly caused by fluctuating water parameters. This disease attacks the fins from the edges.
Several types of flavobacteria are responsible for fin rot, including Columnaris and Aeromonas.
You can treat fin rot by cleaning the aquarium and performing 20 to 50% water changes for at least two weeks.
Megalocytivirus
Johan et al. (2023) were the first to confirm the existence of different possible distribution routes of megalocytivirus in ornamental fish farms in Malaysia that raised angelfish (Pterophyllum scalare); they detected a high Megalocytivirus infection in P. scalare when water temperature, dissolved oxygen, and pH were elevated.
Parasites
Mora-Beltrán et al. (2024) reported the presence of metacercariae of the parasite Clinostomum sp. in a batch of Koi variety scalar fish (Pterophyllum scalare). They applied an antiparasitic treatment using a drug based on Praziquantel and Pyrantel Pamoate (Vermiplex® from ZOO Laboratories); this was administered in a combined manner: orally (25 mg total of Praziquantel and 75 mg total of Pyrantel Pamoate in a mash) and dissolved in the aquarium water (3 ml of dewormer dissolved in the water).
Conclusion
The angelfish is much more than just a pretty face in the aquarium. It is a species with complex and rewarding behavior that, with the right knowledge, can thrive and become the centerpiece of your home. By providing a suitable environment, a balanced diet, and compatible tank mates, you will enjoy the majesty of this incredible fish for many years to come.
Bibliographical References
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Editor at the digital magazine AquaHoy. He holds a degree in Aquaculture Biology from the National University of Santa (UNS) and a Master’s degree in Science and Innovation Management from the Polytechnic University of Valencia, with postgraduate diplomas in Business Innovation and Innovation Management. He possesses extensive experience in the aquaculture and fisheries sector, having led the Fisheries Innovation Unit of the National Program for Innovation in Fisheries and Aquaculture (PNIPA). He has served as a senior consultant in technology watch, an innovation project formulator and advisor, and a lecturer at UNS. He is a member of the Peruvian College of Biologists and was recognized by the World Aquaculture Society (WAS) in 2016 for his contribution to aquaculture.
