|Genus & Species: Pterophyllum Scalare|
|Common Names: Koi Angelfish|
|Temperature: 75 – 86ºF (24 – 30ºC)|
|pH: 6.0 – 7.0|
|GH: 3.0 – 10 dGH|
|Max Size: 15 cm (6 inches) in height and 10 cm (4 inches) in length|
|Lifespan: 10 years|
|Depth Preference: Mid dweller|
|Tank Size: 40 gallons|
Koi angelfish and gold marble angelfish are two phenotypes that have comparable appearances. The distinctive distinction between the two is that only the top of the body, the area around the dorsal fin, and the top of the head are frequently orange on the gold marble angelfish, but the koi angelfish will display more orange across their entire body.
Origin & Habitat
Koi angelfish are a freshwater species of fish endemic to Peru, Brazil, Guyana, Colombia, Suriname, and French Guiana in South America.
In addition to the Solimoes, Amapa, and Amazon basins in Brazil, the Ucayali River in Peru, the Oyapock River in French Guiana, and the Essequibo River in Guyana, they can be found in many different river and drainage systems.
They can typically be found in densely vegetated swamps or floodplains with fallen trees, roots, branches, and leaves littering the substrate in either clear or tannic-stained waters. However, the waters in which they reside are almost always acidic in nature.
Koi Angelfish Care
When properly acclimated, tank-bred koi angelfish are much more versatile than their wild-caught counterparts and can easily tolerate slightly more alkaline conditions.
Through the chemical signals that are released in the form of urine and bile, angelfish can communicate their social status and dominance position. Regular water changes dilute these signals, which leads to more frequent aggressive behavior as they will begin to re-establish dominance.
It has been noted that aggressive behavior can escalate after replacing half of the water in the tank for up to 12 hours before aggression subsides. And the impacts will be milder if only 1/4 of the tank’s water is changed; after an hour, their behavior will return to normal.
Routine water changes should be more frequent while replacing less water rather than large water changes, 1/8 of the tank’s total volume of water or less. This will prevent the dilution of angelfish’s chemical signals and reduce overall aggression within your community tank.
Koi Angelfish Diet & Feeding
The species of Pterophyllum Scalare are omnivorous, largely consuming invertebrates, insect larvae, zoobenthos, plant matter, algae, detritus, and smaller fish in the wild.
They require a balanced diet that includes both algae-based and protein-based foods. Blood worms, tubifex worms, mysis shrimp, insect larvae, and brine shrimp are great sources of food for koi angelfish which are rich in protein.
While they will readily accept most live, frozen, or dried foods, tropical flake or pellets foods specifically formulated for cichlids and at least one form of spirulina will help them maintain a balanced diet. Feeding should occur at least twice a day, anything that can be consumed in under three minutes.
Different diets were used in a controlled 90-day experiment on numerous groups of Pterophyllum Scalare. With a 15 – 25% increase in growth rate when compared to the other diets, they discovered that tubifex performed noticeably better in the growth of angelfish than any other diet they studied.
This is largely attributed to the fact that angelfish are known to preserve energy and choose sources of food that are densely populated in any given location.
Tank Mates & Temperament
Koi angelfish are mildly aggressive social fish that prefer to live in groups of 4 to 6 or more. Males and females may exhibit more aggressive behavior when they pair during breeding seasons or when they are in smaller schools.
Angelfish have social hierarchies; the more dominant individuals will usually be a lot more active and feed more than their inferiors. Isolated angelfish display a lesser degree of activity and feed similarly to lesser dominant individuals.
Ideal koi angelfish tank mates are larger than 2″ and not overly active such as barbs who can easily out-compete the angelfish for food. Larger species of danios, corydoras, dwarf cichlids, gobies, sleepers, livebearers, loaches, tetras, catfish, and plecos are all suitable candidates.
Angelfish can occasionally be kept with species that have long-flowing fins such as bettas, but this would be recommended for experienced aquarists who have a second tank on hand. While carefully monitoring them initially to establish compatibility – temperament can vary.
Male & Female Differences
Identifying the sex of younger angelfish is rather difficult and in most cases impossible; sexual dimorphic characteristics can only be observed in fully matured individuals.
A mature male will typically have a larger and more protrusive crown called nuchal humps (humps or horns on their foreheads) commonly seen in most Cichlidae. On their underbellies next to their ventral fins will be a small tube-like appendage, males will have a thin pointed tube and a female will have either a larger triangular-shaped or blunt tube.
Breeding & Spawning
When a male and female angelfish pair, you’ll notice that they will start to court one another by swimming in a circle or a half-circle while spreading their fins and gills around their preferred mate.
When paired, they will claim a territory and defend it by chasing away their fellow tank mates.
Once you’ve established a breeding pair, immediately remove them from the main community tank and relocate them into a secondary tank with a capacity of at least 30 gallons.
The ideal water conditions for a breeding tank have a pH of 6.5 to 6.9, a water hardness of 7.5 to 10 dH, and a temperature range of 75 to 77 degrees Fahrenheit (25 to 26 degrees Celsius). There cannot be more than 0.1 ppm of ammonia or nitrite nitrogen in the tank.
To begin conditioning the pair of angelfish, a high-protein diet should be frequently provided, particularly one that contains live foods such as mysis shrimp or brine shrimp. Since more care and attention will be needed to maintain the quality of the water throughout this process, live foods do not spoil as rapidly as prepared foods.
In addition, make sure the water’s oxygen content is high enough to support the development of the eggs. As long as the filtration system is generating adequate surface agitation, this will supply enough oxygen. However, the water level in the tank can also be decreased or a silent air stone added to the aquarium to increase surface agitation.
A female angelfish will typically scout out several places and clean them by fanning water before choosing a suitable spawning site to lay her eggs. Adequate spawning sites include flat stones, or aquatic plants like water sprites, tiger lotus, hornwort, and amazon sword, regardless if these plants are live or artificial.
Breeding stimulation can be enhanced by frequent 1/4 tank water changes and then by raising the water level slowly when filling the tank back up.
A large and healthy angelfish is capable of laying up to 1000 eggs, compared to the average 400 to 600 laid by female angelfish. The female will start to lay her eggs, and shortly after, the male will fertilize them. Within 24 to 48 hours, any unfertilized egg will often become white, and the adults will use their mouths to remove any expired eggs.
The pair will continue to fan the eggs with their pectoral fins to provide oxygen to ward off pathogens. If the parents are consistently eating their eggs, the spawning site along with the eggs should be transferred from the breeding tank to a smaller tank.
Pathogens can affect both newly hatched angelfish and their eggs. If you notice that a disproportionate number of eggs are turning white or that newly hatched fish fry are beginning to disappear, you can use either acriflavine or methylene blue, two safe fungicides that prevent and treat the growth of fungus and parasites.
After hatching, the fish fry will become free-swimming 3 to 5 days later and won’t need any dietary supplements during that time, until they’ve depleted their yolk sac. Cultured daphnia, infusoria, and brine shrimp will need to be regularly offered several times a day until they are large enough to accept prepared foods.
To prevent unconsumed food and excrement from contaminating the water, any excess food must be removed and the tank should be cleaned every day. It’ll take roughly two to three months for the fish fry to grow to the size of a quarter.
The Pterophyllum Scalare genus was first described by Schultze in 1823.
Aquarium enthusiasts have produced numerous types and color morphs of the Pterophyllum Scalare genus throughout years of selective breeding.
Contrary to popular myth associated with numerous other sources that claim they can reach sizes of up to 12 inches, even under optimal living conditions, this is just not true. Generally conflating the Pterophyllum Scalare genus with the much larger genus Pterophyllum Altum. On rare occasions, they may grow up to 20 cm (8 inches) in height to 15 cm (6 inches) in length.
K. Sobhanakumar, Kurlan Mathew Abraham, Jayalekshmi. Growth performance of Angelfish, Pterophyllum Sscalare fed with different live worm diets. 2017
Luis M. Gomez-Laplaza, Robert Gerlai. Food Quantity Discrimination in Angelfish (Pterophyllum scalare): The Role of Number, Density, Size and Area Occupied by the Food Items. 2013
Luis M. Gomez-Laplaza, E. Morgan. The influence of social rank in the angelfish, Pterophyllum scalare, on locomotor and feeding activities in a novel environment. 2003
K. N. Mohanta, S. Subramanian. Angelfish: Breeding and Larval Rearing. 1996
Dinelka Thilakarathne, Gayan Nadeela Hirimuthugoda, Tithira Lakkana, and Shalika Kumburegama. Embryonic and larval development in the freshwater angelfish
(Pterophyllum scalare). 2021