WILD DISCUS

Wild Discus

野生七彩神仙

Rio Amazonas Basin (Amazon River Basin)
Discus is endemic to the Rio Amazonas. The river is 6,400 kilometers long with 1,100 tributaries, 17 of which are over 1,400 kilometers re over 3,000 kilometers in length examples are Rio Madeira 3,380 kilometers, Rio Purus 3,211 kilometers, Rio Juruá 3,100 kilometers. It begins in the Andes in the west and eventually flows into the Atlantic Ocean in the east. The Rio Amazonas system transports the largest volume of water of any river system, accounting for about 20% of the total water carried to the oceans by rivers. Most of its water comes from rainfalls along its course and the melting of glaciers in the Andes but the river also drains the Guiana Shield in the north and the Brazilian Highlands in the south.

With an area of 7,050,000 square kilometers, the Rio Amazonas basin is the largest in the world. It covers almost half of South America including Colombia, Bolivia, Ecuador, Peru, Brazil, Venezuela, Guyana, Surinmae, and French Guiana.

The entire basin lies very close to the equator. The climate is always hot and humid throughout the year. The variations between day and night tend to be greater than the variations between seasons. It rains virtually every day, yet there are still a distinct wet and a less wet season. The wet season runs roughly mid-December to mid-May and the less wet season is approximately from August to November. Climate change brought about by global warming produced extremely wet years in 2012, 2021, and serious droughts in 2005, 2010, 2015, all of which devestated or destroyed a lot of the plant and animal communities in Amazonia.

The year-round rain, huge amounts of sunlight and high temperatures have produced a land of tropical evergreen trees growing to 60 meters tall. The water level rises as much as 10-15 meters to flood an immense area of forest during the wet season. The river swells to be as wide as 48 kilometers in certain regions. Many of the smaller tree species have evolved to survive weeks of an annual complete inundation.

As a result of the annual flooding, dense jungles and establishment of Indian reserves, many parts of the river basin are not very accessible until now. There are very few roads in this vast area. Transportation is mainly by boat through the winding rivers.

The most spectacular part of the Rio Amazonas is the Meeting of Waters. It occurs at the city of Manaus where the warm black-water, slow flowing Rio Negro meets the cold white-water, fast flowing Rio Solimões. The difference in composition, flow rate, temperature, and density prevent the two from mixing when they initially meet. This amazing phenomenon stretches for six kilometers. Eventually, the water encounters obstacles that form heavy eddies which churn the two rivers together.

The Rio Amazonas is divided into two parts at the confluence with the Rio Negro; Rio Solimões to the west; Rio Amazonas to the east.

Limnology of Rio Amazonas

Water of this river was divided into three types by the limnologist Dr. Harald Sioli in 1953, which are:

1) White-water rivers—turbid water rich in dissolved solids that also contains a large amount of suspended, nutrient-rich particles from the Andes: pH near neutral or alkaline, conductivity 40-140 μS cm-1.

2) Clear-water rivers—clear greenish water having low amounts of dissolved and suspended solids; pH 6-7, conductivity 10-20 μS cm-1.

3) Black-water rivers—reddish brown water rich in humic acid yet contains very low levels of dissolved solids; pH 4-5, conductivity less than 20 μS cm-1. The characteristic reddish brown water is produced by humic acid leaching out from declaying plant tissues in these slow flowing rivers.

Wild Discus Habitat

Wild discus is found in lakes, lagoons, streams or channels but not inside the main river and its large tributaries. It prefers to live in flooded forest and floodplains (igapós in Portuguese) which are always connected to a large body of water in all three types of black-, white- and clear-water rivers. These lentic habitats have soft and acidic water which are almost free of suspended materials except during the wet seasons. Some populations are found in alkaline water but this is the exception. These discus are the unlucky ones locked in an unfavourable habitat during evolution. They must adapt to survive no matter how harsh the environment is.

Wild discus is a carnivorous, opportunistic feeder. It eats mainly shrimps and bloodworms in its natural habitat. Discus lays eggs on upright submerged branches or rock surfaces if environmental conditions are favorable. It is only during the wet season when there is enough planktonic food to provide a better chance for its larvae to feed and survive.

Nitrification in most discus habitats is carried by fungi, not bacteria because the pH value is too low for the nitrifying bacteria to grow well. Most of the submerged, dead plant materials are also decomposed by saprophytic fungi.

Conservation of Wild Discus Resources

Although Amazonia is very big, discus resources are not inexhaustible. Hydroelectric dams (around 412), deforestation, mining, and farming activities have all contributed to the destruction of discus habitats. Wild discus is only protected by the remoteness of its habitat. Nowadays, the increase in human population, the more frequent use of aeroplanes and faster boats, as well as the construction of more roads and dams are making all wild discus vulnerable to pollution and overfishing. In addition, the serious droughts in recent years have wiped out numerous discus populations when their habitat dried up completely.

Since all the fantastic hybrids in our aquarium were developed from wild ancestors, wild discus is both the past and the future of discus hybridization. The genetic reserve locked in the Rio Amazonas basin is a million times larger than what we have in the aquarium, and there are numerous wild discus breeding every year to result in a tremendous amount of new gene combinations. The occasional massive flood also allows isolated populations to hybridize. If we want to break the inheritance rules of discus in captivity, the best way is to look into wild discus for surprises. For this reason, I was already telling all of my Japanese customers to value them back in the early '90s when they were plentiful and cheap: thousands of boxes were shipped to Japan in a week at a unit price of only 10-25 US dollar.

Taxonomy of Wild Discus

Classification of living organisms originated from the Swedish botanist, zoologist and physician Carl Linnaeus. In his book of 1735—Systema Naturae—he introduced the binomial system of taxonomy, which has been used with minor modifications until today. Linneaus's system is useful to show how organisms are related in the evolutionary tree.

Classification of discus according to the two domain theory is as follows:

Domain—Eukarya; Kingdom—Animalia; Phylum—Chordata; Class—Actinopterygii; Order—Cichiformes; Family—Cichlidae; Genus—Symphysodon; Species—Symphysodon discus Heckel, 1840; Symphysodon aequfasciatus Pellegrin, 1904; Symphysodon tarzoo Lyons, 1959, etc.

A species is further subdivided into subspecies, race, population and strain. A strain refers to closely related organisms derived from inbreeding which are mostly produced by artificial means.

Definition of Species

What is a species? The genetics definition that is generally accepted for many decades is: A species is a group of closely related organisms which can freely interbreed between them to produce fertile offspring. This definition implies crossbreeding between species is not possible or the hybrid is sterile. However, all the five species as recognized by Amado et al. (6) breed freely together to produce fertile offspring.

To make up for the inadequacy of a single definition, there are now morphological species, evolutionary species (ESU, evolutionary significant unit), and even ecological species, which are created according to the need for different fields of biology. The situation is very confusing to everybody, laymen and scientists alike.

From my viewpoint as a breeder, there is only one species of discus, which is S. discus Heckel, 1840. All the other color forms are subspecies.

Genus Symphysodon: Classification History

Johann Heckel was the first person to described Heckel Discus from the Rio Negro in 1840, hence, Symyphysodon discus Heckel, 1840 is the type species of the genus Symphysodon. The holotype was collected at Barra do Rio Negro by Johann Natterer.

The second species—Symyphysodon discus var. aequifasciatus—was described in 1904 by Jacques Pellegrin. Three specimens were used; two from Tefé to represent phenotype green, one from Santarém to represent phenotype brown. (1)

In 1959 Earl Lyons described the third species—Symphysodon tarzoo (2)—based on red spotted Green Discus from Leticia, Colombia. (2)

1960 classification by Dr. Leonard P. Schultz (3)

In 1960 Dr. Herbert Axelrod, founder of Tropical Fish Hobbyist asked his friend Dr. Leonard P. Schultz, curator of fish at the United States National Museum to make a revision on the genus. It is this classification that has been widely used in all kinds of publications until the molecular era of discus taxanomy began in 2006. Dr. L.P. Schultz's classification has two species and three subspecies.

1) Symphysodon discus Heckel, 1840 (Heckel Discus).

2) Symphysodon aequifasciatus is divided into three subspecies:

Symphysodon aequifasciatus aequifasciatus Schultz, 1960 (Green Discus);

Symphysodon aequifasciatus haraldi Schultz, 1960 (Blue Discus);

Symphysodon aequifasciatus axelrodi Schultz, 1960 (Brown Discus).

The specimens utilized by Dr. Schultz were claimed to be collected personally by Dr. Axelrod at the following locations; Green Discus at Tefé, Brown Discus at Santarém, Blue Discus at Benjamin Constant.

1981 revision on Symphysodon discus Heckel, 1840 by Dr. Warren E. Burgess (4)

In 1981 Dr. Warren E. Burgess made a revision on S. discus Heckel, 1840 by the request of Dr. Herbert Axelrod. The work was based on six specimens collected by Dr. Axelrod in the Rio Abacaxis. Dr. Burgess divided S. discus Heckel, 1840 into two subspecies:

Symphysodon discus discus Burgess, 1981 (Rio Negro Heckel);

Symphysodon discus willischwartzi Burgess, 1981 (Rio Abacaxis Heckel).

2006 classification by Ready et. al (5)

According to the 2006 paper by Ready et al., the genus Symphyshon was classified into three species:

1) Symphysodon discus Heckel, 1840 (Heckel Discus);

2) Symphysodon aequifasciatus Pellegrin, 1904 (Brown Discus, Blue Discus, and Royal Blue);

3) Symphysodon tarzoo Lyons, 1959 (Green Discus).

Populations of the Rio Xingú and Rio Tocantins were not included in this study.

2011 classification by Amado et al.

Another paper published in 2011 by Amado et al. (6) divided the genus Symphyson into five species (evolutionary significant units, ESUs) and four genetic groups.

The five species (evolutionary significant units, ESUs)

1) Symphysodon discus Heckel, 1840 (phenotypes Heckel and abacaxis): inhabits western Guyana shield—Rio Negro, upper Rio Uatumã, upper Rio Nhamundá, lower Rio Trombetas; western Brazilian shield—Rio Abacaxis, and other black-water Rio Madeira affluents.

2) Symphysodon tarzoo Lyons, 1959 (phenotype green): inhabits western Amazonia—river drainages west of the Purus Arch*.

3) Symphysodon aequifasciatus Pellegrin, 1904 (phenotype brown): inhabits eastern Amazonia—lower reaches of the Rio Amazonas and its affluents east of the Rio Negro and Rio Solimões confluence.

4) Symphysodon species no. 1 (phenotype blue): inhabits central Amazonia—river drainages east of the Purus Arch and west of the Rio Negro and Rio Solimões confluence.

5) Symphysodon species no. 2 (Xingú group): inhabits eastern Brazilian shield—lower reaches of Rio Tocantins and Rio Xingú.

The authors suggest the scientific name of S. species no. 1 should be Symphysodon haraldi Schultz, 1960. S. species no. 2 has yet to have a scientific name.

* Purus Arch is a low ridge formed in ancient times which transverses the Rio Solimões at the Rio Purus basin.

The four genetic groups

1) group PURPLE—phenotypes Heckel & abacaxis

2) group GREEN—phenotype green

3) group RED—phenotypes blue and brown

4) group PINK—populations of Xingú and Tocantins Rios

None of these genetic groups is pure. Phenotype abacaxis (group PURPLE) has minor mixtures of genes with phenotype brown. Phenotypes blue and brown are both group RED but are also not pure. Phenotype brown has substantial sharings of genes with group PURPLE and minor mixtures of genes with groups PINK and GREEN. Phenotype blue shares some minor genes with groups GREEN and PURPLE. Phenotype Green (group GREEN) has minor mixtures of genes with group PURPLE. Discus from Cametá, Tocantins River (group PINK) shares minor genes with groups PURPLE and GREEN.

References

1) Pellegrin J. Contribution à l’étude anatomique, biologique et taxinomique des poissons de la famille des cichlidés. Memoires. Societe Zoologique de France. 1904;16:41–399.

2) Lyons E. New Blue Discus Electrify Aquarium World. Tropical Magazine- Holiday Issue- 1960, Vol. 4, No. 3.

3) Schultz LP. A review of the pompadour or discus fishes, genus Symphysodon of South America. Tropical Fish Hobbyist 1960: 8:5-17.

4) Burgess WE. Studies on the family cichlidae: 10. New information on the species of the genus Symphysodon with the description of a new subspecies of S. discus Heckel. Tropical Fish Hobbyist. 1981;29:32–42.

5) Ready JS, Ferreira EJG, Kullander SO. Discus fishes: mitochondrial DNA evidence for a phylogeographic barrier in the Amazonian genus Symphysodon (Teleostei: Cichlidae) Fish Biology. 2006;69:200–211.

6) Manuella Villar Amado, Izeni P. Farias and Tomas Hrbek. A Moelcular Prespective on Systematics, Taxonomy and Classification Amazonian Discus Fishes of the Genus Symphysodon. Int J Evol Biol. 2011; 2011: 360654. doi: 10.4061/2011/360654. Epub 2011 Jul 28.

Description of the Species

While there are still a lot of debates about whether the genus Symphysodon should be divided into five species, for the sake of clarity, I shall use the 2011 Amado et al. classification in all my writings about wild discus.

ABOVE: Negro Heckel Discus, photo courtesy of Jörg Schütz, Germany

ABOVE: Paunini Heckel, photo courtesy of Pet Balloon, Japan

ABOVE: Paunini Heckel, photo courtesy of Pet Balloon, Japan

ABOVE: Uatuma Heckel, photo courtesy of Pet Balloon, Japan

ABOVE: Upper Nhamunda Heckel, photo courtesy of Pet Balloon, Japan

ABOVE: Upper Nhamunda Heckel, photo ourtesy of Pet Balloon, Japan

ABOVE: Upper Nhamunda Heckel, photo courtesy of Justin Chen, Taiwan

ABOVE: Rio Abacaxis Heckel

ABOVE: Rio Abaxacis Heckel

Symphysodon discus Heckel, 1840: phenotypes Heckel & abacaxis; Common Name—Heckel Discus

Distribution

Heckel Discus is found in Rio Negro, upper Rio Uatumã, upper Rio Nhamundá, lower Rio Trombetas, Rio Abacaxis, and some other black-water affluents of Rio Madeira. It lives in black-water habits: pH 4.2-5.2, conductivity less than 20 μS cm-1, temperature 26-32°C.

Classification History

Johann Heckel described Heckel Discus from the Rio Negro in 1840. Because it was the first species to be described in science, S. discus Heckel, 1840 is the type species of the genus Symphysodon.

In 1981 Dr. Warren E. Burgess subdivided the species into two subspecies: S. discus discus Burgess, 1981 (Rio Negro Heckel and S. discus willischwartzi Burgess, 1981 (Rio Abacaxis Heckel) (4).

Both the 2006 study by Ready et al. (5) and the 2011 paper by Amado et al. (6) abolished the classification by Dr. W. E. Burgess (4) to group all Heckel Discus as S. discus Heckel, 1840.

Genetics

According to Amado et al. (6), this species is a very pure and distinct genetic group PURPLE. Phenotype Heckel genes are found all over the whole distribution range of the genus Symphysodon, from Green Discus that inhabits the head-waters of the Rio Solimões in Peru to the Cametá population on Rio Tocantins near its mouth. Can this phenomenon be the evidence that Heckel Discus was the first discus species to appear in the Rio Negro, then spread to all the major tributaries of the Rio Amazonas to evolve into the other species after millions of years' isolation and adaption?

Genetic Variations within the Species

Heckel Dicus from the Rio Negro Drainage are the pure form of S. discus Heckel, 1840.

The Abacaxis phenotype is limited to Rio Abacaxis and several other small black-water tributaries of the Rio Madeira which contains a few genes from phenotype brown.

Discus caught at Porto Trombetas, a town/port about 110 kilometers upstream from the river's mouth is close to the pure group PURPLE. It also contains minior group RED genes, a trace of group GREEN genes, and a few group PINK genes.

Heckel Discus also lives in the upper course of the Nhamundá and Uatumã Rios but they were not included in the 2011 study by Amando et al. (6) Hence, there is no data to elucidate whether they are also the pure form of this species.

Morphology

S. discus Heckel, 1840 is characterised by the dark and wide central Heckel Bar, which is the fifth of the nine vertical bars that are found in all wild discus. There are also pale blue, almost non iridescent, horizontal stripes on the whole body. Body form is the roundest of all the species in the genus Symphysodon. This species has an average length of 12-17 cm.

Morphological Variations within the Species

Rio Negro Drainage

Heckel Discus from the main river has a deep brown body color with a reddish tint. There is also a very high concentration of melanophores to give a grey appearance and dark eyes to the fish. Some individuals have a solid patch of turquoise color on the head and operculum, which are called "Blue Face Heckel" in the discus trade.

Rio Branco, a big tributary having a water quality intermediate between white-water and clear-water, produces Heckel Discus with a lighter brown basic body color and a more greenish turquoise color.

Discus from Unini and Paunini Rios resemble those from the main river except for a longer, thinner body, a more bluish hue to the turquoise color, and the presence of a grayish bluish haze on the whole body. In recent years, Brazilian exporters have been selling introduced Heckel Discus bred in Rio Unini looking different from the endemic ones.

Rio Abacaxis Drainage

The abacaxis phenotype has a body color ranging from yellow, yellowish orange to reddish brown. It also has red and other light color eyes.

Rio Uatumã Drainage

According to Mr. Masahiro Uemura, proprietor of Pet Balloon, Japan, Heckel Discus from this river resembles those from the Rio Negro except being a little smaller in size.

Rio Nhamundá Drainage

There is a special variant in the upper reach of this river having a pale turquoise blue film on the whole body and a solid patch of turquoise color on the head and operculum. The Heckel Bar has a reduction in both its intensity and width. It is called Blue Moon by Mr. Hudson Crizanto Gonçalves, proprietor of H&K Peixes ornamentais ltda, which most probably is not purely S. discus Heckel, 1840.

Rio Trombetas Drainage

In the past few years, Mr. Hudson Crizanto Gonçalves was selling Heckel Discus from Rio Cuminã, a remote secondary tributary of Rio Trombetas (roughly 70 kilometers straight distance upstream) which flows into the Rio Paru de Oeste. Rio Cuminã Heckel also has a light turquoise blue film on the body overlaying the turquoise stripes. This film is so strong in some fishes that they appear to be solid turquoise. This rather unique variety should not be the pure form of S. discus Heckel, 1840. It most probably also contains genes from phenotype brown, but the truth can only be revealed by a DNA analysis.

Mr. Uemura has observed throughout the years there is a gradual fading of the turquoise film in all varieties of Heckel Discus in the aquarium and all "Blue Face Heckel" becomes the normal Rio Negro Heckel within a few weeks after arrival to Japan. There is even a possibility these films are enhanced or produced artificially in the aquarium.

Merits in Hybridization

The F1 generation hybrids from Rio Negro and Rio Abacaxis Heckels have a grey film on the fish's whole body which gradually covers upon all the other colors. Heckels are not useful for hybridization. It is for the same reason that I do not recommend using them for the creation of Brilliant Turquoise.

ABOVE: Rio Abacaxis Heckel X WB2 Cobalt Blue F1

I crossed a Rio Abacaxis Heckel with WB2 Cobalt Blue in 1995. The F1 generation offspring have wide stripes and a gray film on the body. The Heckel bar is missing in most of them. In a few fishes it appear as a short 2-3 cm tall bar in the middle of the body.

ABOVE: Rio Negro Heckel X Rio Manacapuru Royal Blue F1 bred by Jörg Schütz, Germany

Jörg Schutz also sent me some F1 generation offspring from Rio Negro Heckel cross Rio Manacapuru Royal Blue in 1987. These look like a Heckel Discus in all respect except without the Heckel Bar.

Many years ago, Dr Schmidt-Focke crossed a Heckel Discus (S. discus Heckel, 1840) male with a female Blue Discus (S. aequifasciatus Pellegrin 1904). In the F1 generation, all fish have the Heckel Bar but 30% of them have a very weak one. In the F2, the Heckel Bar becomes rare. In one fish there are two dark bars only on one side of the body. The Heckel Bar disappears completely in the F3 inbreed generation.

The inheritance of the Heckel Bar is confusing. More researches are needed to uncover its secret.

The Rio Negro Heckel have the highest concentration of melanophores in the five species of wild discus as classified by Amando et. al (6). Red Royal Blue that has a lot of black cells and a trace of the Heckel Bar should have Heckel Discus genes.

Symphysodon aequifasciatus Pellegrin, 1904

This is a controversial species. In the original 1904 paper by Jacques Pellegrin, it is known as S. discus var. aequifasciatus. Two phenotype green fishes collected in Tefé and one phenotype brown specimen from Santarém were used in the description.
In his 1960 classification, Dr. Leonard P. Schultz divided the species into three subspecies: S. aequifasciatus aequifasciatus Schultz, 1960 (Green Discus); S. aequifasciatus haraldi Schultz, 1960 (Blue Discus); S. aequifasciatus axelrodi Schultz, 1960 (Brown Discus).

The 2006 classification by Ready et al. abolished the subspecies status and restored S. aequifasciatus as a single species.
In the latest 2011 classification by Amado et al., phenotype brown found east of the Rio Negro, Rio Solimões confluence and phenotype blue living west of this confluence are given a status of two separate species. In this classification, the scientific name of phenotype blue is S. haraldi Schultz, 1960 or S. species no. 1. S. aequifasciatus Pellegrin, 1904 is the name for phenotype brown. Nevertheless, there is still a lot of debate about this division, which is based on the tiny amount of Xingú group genes (S. species no. 2) found only in S. aequifasciatus Pellegrin, 1904.

The 2006 classification by Ready et al. does not include populations of Xingú and Tocantins Rios while the 2011 Amado et al. classification gives them a species status: S. species no. 2.

Symphysodon species no. 2 (6); Xingú and Tocantins Populations; Common Name—Brown Discus

Distribution

This species lives in the clear-water habitats of the lower Rio Xingú (1,640 kilometers long) and Rio Tocantins (2,450 kilometers long).

Genetics

The species is classified as belonging to the genetic group PINK in the 2011 paper by Amado et al. (6) The Vitória do Xingú (Rio Xingú) population is purely group PINK. The Cametá population (Rio Tocantins) shares minor genes with groups PURPLE and GREEN.

Morphology

Members of this species do not have a Heckel Bar. They have a brown body and short fins. A few turquoise stripes are found only on the head and the dorsal, anal, pelvic fins. Before Manaus took over as the tropical fish export center in South America in the 1960s, many of them were exported as Brown Discus* from Guyana in the 1940-'50s. They were caught in the lower Rio Amazonas and were transported by ship together with other tropical fishes to Georgetown, Guyana from Santarém or Belém to be exported worldwide.

*For a long time, the scienific name of Brown Discus was S. aequifasciatus Axelrodi Schultz, 1960 (3) until it was abolished by Ready et al. in 2006.

Merits in Hybridization

Although a large number of the so-called Brown Discus were bred in Hong Kong and Thailand in the late 1950s to '70s, very few fishes of this species have been used in the production of exotic hybrids. Therefore, we have very little information about its genetic merits.

Symphysodon haraldi Schultz, 1960 (6) or Symphysodon species no. 1 (6); phenotype blue; Common Name—Brown Discus, Blue Discus, and Royal Blue

Habitat

S. haraldi Schultz, 1960 lives in central Amazonas east of the Coari region on the Rio Solimões and west of the confluence of Rio Negro and Rio Solimões in white- and black-water habitats. During the past decades, no Green Discus (S. tarzoo Lyons, 1959) has ever been found east of Coari and S. haraldi schultz, 1960 does not exist west of Coari. Therefore, it is reasonable to say Corai region is the boundary of the two species rather than the elusive Purus Arch as stated in the 2011 paper by Amado et al.

Genetics & its Variations

This species belongs to the genetic group RED. However, there are small variations in the population from different locations that also contain group GREEN and PURPLE genes.

Morphology

These are small discus with an average length of 11-16 cm. Body form is oval. Heckel Bar is absent in the majority of phenotype blue. Most of them only have turquoise stripes on the head, the operculum and the dorsal, anal, pelvic fins. Fully striated specimens are quite rare. There is a wide black ring on the dorsal and anal fins. The body color is various shades of brown or orange. When the discus fishery began near Manaus began in the 1960s, many of the poorly striated phenotype blue fishes were exported from Manaus as Brown Discus.

Trade Names: Blue Discus, Royal Blue

Blue Discus

The Blue Discus (known scientifically as S. aequifasciatus haraldi Schultz, 1960 (3) from 1960 until 2006) has been associated with this species for a long time. It is very similar to Brown Discus with the exception of more turquoise stripes on the fish's back and the abdomen. There are no turquoise stripes in the center of the body in this variety. For decades, the so-called Blue Discus were actually better striated phenotype blue specimens that were selected from a shipment of the so-called Brown Discus from central Amazonas to be sold at a higher price by Manaus exporters. In recent years, this type of discus with half body striation from both phenotypes blue and red are called "Semi Royal Blue" in the discus trade.

Royal Blue

The most famous color form of S. haraldi Schultz, 1960 is Royal Blue. This is a name created by Willi Schwartz to describe the rare, fully striated phenotype blue specimens. He began to export Royal Blue from Rio Purus at around the mid 1960s.

Morphological Variations within the Species

Rio Purus Drainage (white-water)

The classic Rio Purus Royal Blue of the 1960-'70s is a rather small discus that rarely exceeds 13 cm in length. Body color is a light to medium brown and the turquoise color is more greenish than bluish. In a good specimen, the turquoise stripes continue through the black band on the dorsal and anal fins to terminate at their edge. The body form is also quite distinctive. They have a pointed mouth, a slightly long body, as well as high dorsal fin and anal fin. Some specimens show a very weak Heckel Bar during breeding.

Nowadays, the main fisheries in the Rio Purus drainage are at Lago Surará, Lago Sitar, Lago Aiapurá, Lago Uauaçu, Lago Jari, Paraná São Tomé, and Mutuka. The discus caught in these locations are larger than the classic Royal Blue.

Rio Manacapuru Drainage (black water)

Excellent Manacapuru Royal Blues were available in Germany in the early 1980s. These are 13-15 cm discus having wide blue stripes on a medium to dark brown body. Some of the good specimens have patches of solid turquoise on the anal fin which is a morphological expression of sharing genes with Green Discus through introgression.

According to Mr. Uemura, good quality Royal Blues from this region has been exhausted for at least 25 years. Only some solid orange discus are being exported from the Manacapuru drainage nowadays.

Anori Region

Another area that also produces good Royal Blue specimens is around Anori, a municipality located about 195 kilometers south west of Manaus on the north bank of the Rio Solimões. Mr. Uemura remarked that many of the so-called Anori Discus are actually caught in the Rio Purus drainage.

Iranduba/Mamuri (Mamori) Region

According to Mr. Ismael Silva de Oliveira, there are excellent, Royal Blue, Blue Discus, and Brown Discus living in this region. Body colors are brown, reddish brown and orange.

Merits in Hybridization

Royal Blues from Rio Purus have been important in the history of discus hybridization as the source of wide, parallel, iridescent turquoise stripes and high fins. They are the ancestors of all the important hybrid strains such as Schmidt-Focke Red Turquoise, the Schulten strain, the Jesiorsy pair, Mack's Powder Blue strain, and Discus Heaven's Albino Discus.

ABOVE: Doctor's Royal Blue in the '70s, photo courtesy of Mr.

Burkard Kahl, Germany

ABOVE: Rio Manacapuru Royal Blue F1 bred by Jörg Schütz,

Germany, photo courtesy of Jörg Schütz, Germany

ABOVE: Doctor's Rio Manacaouru Royal Blue, photo courtesy

of Dr. Schmidt-Focke, Germany

ABOVE: Rio Manacapuru Royal Blue

ABOVE: Wild Royal Blue from an unknown location

ABOVE: Doctor's Rio Manacapuru Royal Blue, photo

courtesy of Dr. Schmidt-Focke, Germany

ABOVE: Wild Green Striped Discus F1 from Dr. Schmidt-Focke (Rio Purus?)

ABOVE: F2 Rio Manacapuru Royal Blue bred from Jörg Schütz's F1 offspring

Symphysodon aequifasciatus Pellegrin, 1904; phenotype brown; Common Name—Red Discus, Brown Discus, Blue Discus, Royal Blue, Heckel Cross

Distribution

This species inhabits East Amazonas in the lower reaches of the Rio Amazonas and its tributaries east of the confluence with Rio Negro. It lives in white-, black- and clear-water rivers: black-water habitats—Canumã-Sucunduri, Marimari, Paraconi, Maués Açu Rios, Urubu and Uatumã Rios, some water bodies on the lower Nhamundá and Trombetas Rios, certain lakes and channels between Alenquer and Curuá (Rio Solimões), Lago Grande do Curuai (Rio Solimões); white-water habitats—Rio Solimões; clear-water habitats—Nhamundá, Trombetas, Tapajós Rios.

Genetics

S. aequifasciatus Pellegrin, 1904 is a big mixture of all the four genetic groups. Discus from different locations inside the vast distribution area of this species are rather different in their genetic composition. It is really fascinating that such a diversity in genetic compositions produce discus looking so similar.

Morphology

Besides wide distribution, phenotype brown also has the largest number of color forms. There is a big mixture of fishes looking like Brown Discus, Blue Discus, Royal Blue, and Heckel Discus living in the same habitat within its major distribution range. The body color ranges from yellow, light yellowish brown to dark brown, or from orange red to deep red. Most of them only have striations on the forehead, the operculum, abdomen and the dorsal, anal, pelvic fins. The center of the body has no stripes. There are also half body striped to fully striated fishes. A lot of them have the Heckel Bar in various intensities which are called "Heckel Cross" by hobbyists. Body form of phenotype brown is rounder than phenotype blue. Average length of the species is 13-18 cm. Due to its round body form and big size, this is the favorite wild discus species in Asia nowadays.

The New "Royal Blue"

In recent years, the full striated discus of this species is called "Royal Blue" in the discus trade. They make up nearly 100% of the so-called "Royal Blue" which are being sold nowdays. The fact that a lot of the new "Royal Blue" has a rather prominent Heckel Bar on its body, it is quite impossible to distinguish it visually from the so-called "Heckel Discus" and "Heckel Cross" found in the basin of the Madeira, Uatumã, Nhamumdá, and Trombetas Rios.

In comparison, the old Royal Blue from phenotype blue does not have a prominent Heckel Bar and also has more iridescent turquoise stripes.

Genotypes Versus Phenotypes

Rio Madeira Drainage (white-water, 3,380 kilometers)

This river is the biggest tributary of the Rio Amazonas, accounting for roughly 15% of the water in the basin. Like the Rio Purus, discus does not live in the main river. The floodplains to the east of the river, in the region roughly between Paraná do Urariá in the north and Novo Aripuanã in the south, are where some of the most beautiful and genetically interesting wild discus are found. It is a vast area; approximately 300 kilometers east to west and at least 200 kilometers north to south.

It was in this region where Dr. Harald Schultz caught the three specimens for Dr. Schmidt-Focke in 1959. Dr. Herbert Axelrod also collected the six Heckel Discus in the Rio Abacaxis which were used for classification by Dr. Warren E. Burgess in 1981.

The main discus producing rivers in this area are Rio Canumã-Sucunduri (900 kilometers), Rio Marimari, Rio Abacaxis (610 kilometers), Rio Paraconi, and Rio Maués Açu (370 kilometers). These are black-water secondary tributaries flowing into Parana do Urariá which is connected to Rio Madeira via the short Paraná do Canumã, and to Rio Amazonas through the much longer Paraná do Ramos.

I saw at least 30,000 discus from this region when I was in Manaus hunting for wild discus in 1994. The most impressive are two types of Red Discus. The first type is the small (11-13 cm long) yet firely red specimens from the Rio Maués Açu. This river receives water from Rio Paraconi and Rio Amanã. Its lower course is known as Rio Parauari. The town of Maués, where the discus are said to be caught in its surroundings, is located on the eastern bank of Rio Parauari near the point it merges with Paraná do Urariá.

The second type is the larger, 13-15 cm long Paraconi Discus. While discus from the Rio Paraconi are perfectly round, the Maués Açu fishes have a long body. Only about 10-15% of both varieties have a medium size Heckel Bar.

There were also hundreds of discus which were said to be caught nearby Novo Olinda do Norte, a small town/port located roughly 70 kilometers from the mouth of Rio Madeira and 125 kilometers south west of Manaus. The town is a very convenient place to begin a fishing trip in the region. Rio Canumã is about 10 kilometers south, Rio Abacaxis roughly 35 kilometers west, Rio Paraconi about 125 kilometers north west, and the town of Maués approximately 155 kilometers north west. All the discus caught in this vast area are transported to this small town as the stopover place before being shipped to Manaus for export. Therefore, those that I saw might not be caught locally.

The Novo Olinda do Norte Discus of the 1994-'95 season has a deep red body and a strong Heckel Bar. Males are fully striated with wide and iridescent turquoise stripes all over the whole body. Females are only 1/2-2/3 striated. These are the best natural versions of Heckel Red Turquoise that I have ever seen.

Discus from Rio Marimari, a right tributary of Rio Abacaxis, has a yellowish brown to orange red body. Most of them have a rather strong Heckel Bar and turquoise stripes on 1/2-2/3 of the body but there are also full striated specimens. There are also a few unique lemon yellow individuals having no body striation except for a few short bars inside the Heckel Bar. According to its mood, Marimari Discus can control the color of its Heckel Bar from black to white or vice versa.

Rio Canumã-Sucunduri is the longest river in this region. Mr. Uemura has been importing various types of solid yellow discus with or without Heckel Bar from unspecified locations on the Rio Canumã for years. In 2016 Mr. Hudson Crizanto Gonçalves collected fully striated specimens with a strong Heckel Bar on Rio Sucunduri which he called Heckel Discus, but they are a big mixture genetically having a substential amount of group RED genes, and some group GREEN genes besides group PURPLE genes.

ABOVE: Novo Olinda do Norte Discus

ABOVE: Novo Olinda do Norte Discus with strong Heckel bars

ABOVE: Novo Olinda do Norte Discus

ABOVE: Nove Olinda do Norte Discus

ABOVE: Novo Olinda do Norte Discus

ABOVE: Novo Olinda do Norte Discus

ABOVE: Marimari Discus

ABOVE: Rio Marimari Discus

ABOVE: Rio Marimari Discus

ABOVE: Lemon yellow Rio Marimari Discus, photo courtesy of Manfred Göbel, Germany

ABOVE: Rio Maderia Discus (Jungle Pearl)

ABOVE: Rio Paraconi Discus, photo corutesy of AIC Kumamoto Tropical

Fish, Japan

ABOVE: Rio Paraconi Discus, photo corutesy of AIC Kumamoto Tropical

Fish, Japan

ABOVE: Rio Paraconi Discus, photo of corutesy AIC Kumamoto Tropical

Fish, Japan

ABOVE: Rio Paraconi Discus

ABOVE: Rio Maués Açu Discus, photo courtesy of Manfred

Göbel, Germany

Rio Urubu and Rio Uatumã Drainage (black-water)

The discus collected at Itapiranga, a town on the bank of Rio Uruba and the lower reaches of Rio Uatumã are Brown Discus, Blue Discus, and Royal Blue types of discus possessing blue turquoise stripes and body colors ranging from brown to reddish brown. They are small, 13-15 cm long discus with a slightly long body. Most of them do not have a Heckel Bar.

Rio Nhamundá Drainage (clear-water)

The major fishery sites of the river are at the lower reaches of the river such as Lago do Guarabi (Lake Guariba), Lago Espelha, Maracanã Village, as well as water bodies around the small towns of Nhamundá, Faro, and Terra Santa. According to Mr. Hudson Crizanto Gonçalves, all of these fishing locations have black-water.

The discus caught in these regions are popular nowadays that consist of full striated, half striated, and solid varieties with a brown to reddish brown body. Surprisingly, most of them do not have a strong Heckel Bar.

Lago do Guarabi is approximately 15 kilometers south west of Nhamundá. Inside the lake, besides the normal phenotype brown types are populations resembling those from upper Rio Nhamundá. These full striated discus have a rather strong Heckel Bar and a patch of solid turquoise on the head and operculum, as well as a grayish bluish film on the whole body. These are known as "Heckel Cross" commercially. There is no doubt most of them share substantial genes with the Heckel phenotype.

Rio Trombetas Drainage (clear-water)

All the phenotype brown varieties are found in its lower course. The main fishing grounds are a cluster of black- or white-water lakes suchs as Lago Iriprixi, Lago Caipura, Lago Archipicá, Lago Samauma, and Lago Curupira. Lago Iriprixi is situated right next to Oriximiná and São Raimundo, the two major towns of the river.

There is a great variation in both the intensity and width of the Heckel Bar among the phenotype brown discus caught in this roughly 30 kilometers section of the lower Rio Trombetas.

There are no discus fisheries in the upper reaches of this river. Discus cannot survive in rivers having rapid currents and cataracts.

ABOVE: Rio Uatuma Discus, photo courtesy of Mr. Sadaaki Hachiya, Japan

ABOVE: Rio Nhamunda Discus, photo courtesy of Mr. Justin Chen, Taiwan

Alenquer Curumucuri (Mizukoshi Yoshinori

ABOVE: Lagoa Grande West Discus (Mr. Onoda's secret lake),

photo Courtesy of Mr. Sadaaki Hachiya, Japan

ABOVE: Alenquer Discus, photo Courtesy of Mr. Mizukoshi Yoshinori, Japan

ABOVE: Solid Red Discus obtained from Dr. Schmidt-Focke in 1990. Alenquer or Cuipeua ?

ABOVE: Alenquer Discus offspring, photo courtesy

of Manfred Göbel, Germany

ABOVE: The Göbel line of Alenquer Discus bred by Mr. Hiroshi Irie in Japan, photo Courtesy of Hiroshi Irie, Japan

ABOVE: Cuipeua Discus from the 2011 Jorg/Hermann expedition, photo

courtesy of Mr. Hubert Kleijkers, Netherlands

ABOVE: Cuipeua Discus, photo courtesy of Mr.

Hubert Kleijkers, Netherlands

ABOVE: Inanu Discus, photo courtesy of Mr. Sadaaki Hachiya, Japan

ABOVE: Lago Curumucuri discus, photo courtesy of Pet Balloon, Japan

Cuipéua/Alenquer Discu

Another major source of phenotype brown discus comes from the lakes, lagoons, streams, and small rivers along a roughly 40 kilometers (straight distance) stretch on the north shore of the Rio Amazonas from Curuá in the west to Alenquer in the east. Alenquer is a small town roughly across the city of Santarém on the north bank of the Rio Amazonas. Cuipéua is a small village about 20 kilometers to the west of Alenquer. Curuá is a town located approximately 15 kilometers west of Cuipéua. Although nobody other than Arthur Werner has been able to catch the deep red original Alenquer Discus from and around the town of Alenquer, nevertheless, all the discus caught within this region are sold collectively nowadays as Cuipéua/Alenquer Discus.

The original fishing ground of this variety is a small lake at the Cuipéua Village but the good specimens have been exhausted for more than a decade. Nowadays discus are collected in water bodies around the small towns of Curuá such as Lago Curuá, Lago Makita, and Lago Saoluise. Lago Mangel and Barra Mansa Village are the other favorite fishing locations. Discus are also caught at places around Alenquer such as Lago Uruxi, Lago Murué, Lago Capintuba, Lago Curicaca, Lago Macocáua, and Lago Paracari. In addition, there are many small fisheries nearby small villages, streams or lagoons inside this 40 kilometers section of the Rio Amazonas, many of them do not even have a name. Mr. Hudson Crizanto Gonçalves said these habitats have a wide range of water quality from pure black-, clear- and white-water to different mixtures of the three types.

None of the Cuipéua/Alenquer Discus offered for sale in the market nowadays resembles the orange red discus caught at the Cuipéua Village by the 2001 Jörg/Hermann expedition. Most of them have a brown or at most brownish red body. Some also have a medium size Heckel Bar which is absent in WW69 Millennium Red, the strain developed by Jörg Schutz from the Cuipéua discus caught in 2001.

Lago Grande do Curuai [Grand Lake of Curuai in English] (black-water)

Lago Grande do Curuai is a big south shore lake that is connected to the Rio Amazonas. Its nearest portion is roughly 40 kilometers west of Santarém. There is a big variety of discus caught in this lake, non striated, half striated to full body striped. Body colors are from yellowish brown to brown and also various shades of red. Body form can be oval or round. Quite a few of the discus caught in this lake have a medium size Heckel Bar. A lot of the so-called Alenquer/Cuipéua Discus that are being sold nowadays come from this lake.

There are as many as 200 small villages surrounding the lake. The most famous one is Inanu that produces a special type of round to high body solid color, half striped and fully striated reddish discus. There are only 30-40 families living in the Inanu village. Other fishing locations are at Traira, Curuai, Mata Limpa, and Urariá Villages, just to name a few. Lago Itelvina and Lago Carananzaru are small lakes connected to Lago Grande do Curuai that also produce high quality discus.

Lago Curumucuri [Lake Curumucuri in English] (clear-water)

Lago Curumucuri is a rather large lake south of the Rio Amazonas, about 150 kilometers north east of Santarém and less than 10 kilometers south west of Juriti, the closest town. It is a few kilometers from the bank of Rio Amazonas in the dry seasons but the lake should be connected with the main river during the wet seasons.

Living in this lake are discus populations having the strongest greenish blue film within the species. The body color is various shades of brown ranging from yellowish to reddish. Some specimens have small red blotches on the body. Turquoise striping varies from only a few on the head and fins to full body striation. Some of them also have a medium size Heckel Bar. According to Mr. Hudson Crizanto Gonçalves, these are big discus up to 19 cm long.

Rio Tapajós Drainage (clear water)

Tapajós Discus is not popular. The only known variety is Maicá Discus, named after a lake located on the outskirts of Santarém. Mr. Hudson Crizanto Gonçalves told me these are Brown Discus type discus which are not high in quality or big in size.

Rio Jari Drainage

Discus from this river is phenotype brown but there are no discus fishery in this river.

Merits in Hybridization

Nowadays, nearly all the so-called Red, Brown, Blue Discus, and Royal Blue are caught from the same habitat in the drainage of Madeira, Uatumã, Nhamundá, and Trombetas Rios. These discus are big mixtures of all the four genetic groups (6). They are produced by a very long period of random hybridization that might have begun even before the speciation of Symphysodon. In the aquarium, Red Royal Blue was created in Thailand in exactly the same way many years ago.

Most populations of this species contain a fair amount of Heckel Discus genes to result in having pale blue stripes with little iridescence and a Heckel Bar of various intensities. I have failed to breed Rio Madeira Discus with a strong Heckel Bar, irrespective of body striation and color. It is wise to breed with non Heckel Bar specimens or those having a very weak one. Expect to have problems when working with this species. Besides taking a longer time to create a strain (Red Royal Blue took 12-15 years), there is also the possibility of a gray film appearing on the whole body (as in the case of Red Royal Blue), which destroys both the fish's color and those of its offspring.

Symphysodon tarzoo Lyons, 1959; phenotype green; Common Name—Green Discus, Solid Green, Royal Green, Red Spotted Green, Brazilian Gold

Distribution

Green Discus is found in west Amazonia upriver from the Coari region of the Rio Solimões. This species is found in black-water and white-water habitats: pH 4.8-5.9, conductivity 20-140 μS cm-1, temperature 27-30°C.

Most Green Discus being sold nowadays are caught in the drainage of Tefé, Juruá, Japurá, Jutaí Rios in Brazil; Brazilian and Peruvian sections of the Rio Içá/Putumayo; lower Rio Napo, Rio Nanay in Peru; and some minor fisheries in the Coari region of the Rio Solimões in Brazil.

The populations found in Rio Nanay, a tributary of Rio Solimões that flows through the Peruvian city of Iquitos, are most probably descendants from introduced Green Discus. According to Marc Weiss, an Iquitos fish breeder named Bustamante collected Green Discus from Rio Içá/Putumayo and Rio Tefé in the 1970s. He put them into a small, contained lake to breed naturally. The discus escaped into the Rio Nanay during the wet season when floods connected the lake with the river but the validity of this piece of information can only be determined by a DNA analysis.

Classification History

Green Discus was first described by Jacques Pellegrin in 1904 as S. discus var. aequifasciatus based on two specimens from Tefé. A single fish from Santarém to represent phenotype brown was also included in his paper. (1)

Earl Lyons wrote an article entitled "New Blue Discus Electrify Aquarium World" in the magazine—Tropicals: Holiday Issue: 1960, vol. 4, no.3 —in which he described a new species of discus based on red spotted specimens from Leticia, Colombia (2).

In 1960, Dr. Leonard P. Schultz rejected the name S. discus tarzoo to classify Green Discus as S.aequifasciatus aequifasciatus Schultz, 1960 (3), even though he was aware that E. Lyon submitted his article to the magazine publisher in Nov. 28, 1959 (3).

In both the 2006 Ready et al. (5) and the 2011 Amado et al. (6) classifications, S. tarzoo Lyons, 1959 was restored as the scientific name of Green Discus (phenotype green).

Genetics

The Amado et al. 2011 paper (6) designates Green Discus to group GREEN. Except for sharing a small amount of genes with group PURPLE, this is a rather pure genetic entity.

Morphology

S. tarzoo Lyons, 1959 is the only species in the genus Symphysodon having red spots with the exception of certain phenotype brown specimens. It was discovered in recent years that some specimens from the Rio Paraconi (a secondary tributary of Rio Madeira) have a small amount of small, not so vivid, red spots. A small number of fishes with faint red blotches on the body were also caught in Lago Grande do Curuai and Lago Curucumuri.

The turquoise color of this species is more on the green side than blue which occurs in different forms. Their body form is long. A lot of Green Discus have a rather big cephalic hump. Average length of this species is 12-16 cm. Body color can range from a light yellowish brown to a deeper shade of brown or even orange. Those specimens that have a light brown or orange body invariably also have a characteristic yellowish brown (golden) abdomen. All phenotype green has a solid black band on the dorsal and anal fins, which are often delinerated both on the inside and outside by a complete or incomplete ring of turquoise color. Radiating outwards from the black band are fine and short, backward pointing turquoise lines. The fringe of both fins can be deep red, yellowish brown or colorless. Green Discus has more populations with a long streamer on the dorsal fin than all other discus species.

As a result of sharing genes with phenotype Heckel through introgression, Heckel Bar is present in various reduced intensities in a good percentage of Green Discus. There is also an enhancement of the 6th and 7th bars during breeding or when the fish is stressed.

Trade Names—Green Discus, Solid Green, Royal Green, Red Spotted Green, Brazilian Gold

There are five major color forms in the discus trade. The common Green Discus does not have red spots. It has a brown body overlain with a greenish haze. The turquoise stripes are found only on the head, the operculum and the dorsal, anal, pelvic fins. Those having a very strong film are called Solid Green. The third variety is known in the aquarium trade as Royal Green. The best fishes are fully striated with wide and linear turquoise stripes from head to tail. Average quality ones only have stripes on the anterior half of the body. Most of them have red spots in between the stripes. The fourth type is the Red Spotted Green. It has a brown or light orange body and red spots. Turquoise color appears as wavy, somewhat broken stripes on the body and as blotches on the fish's periphery. The rarest color form has vivid and small, brilliantly red spots on a solid yellowish brown (golden) or orange body. The turquoise stripes are present as short stripes and patches only on the periphery of the discus. I named this exquisite group Brazilian Gold.

Morphological Variations within the Species

Coari Region (black-water)

This is the region where phenotype green mixes with phenotype blue. According to Mr. Ismael Silva de Oliveira, proprietor of Ismael Aqua Fish, the discus from Lago Mamiá are half striated to fully striated which are not Green Discus. There are Green Discus living in the drainage of Panará Copeá and Rio Coari Grande. Some of them have red spots.

In 2000 there were several expeditions organized by Mr. Uemura to collect discus in this region; the exact locations are unknown. The Manaus discus exporter K2 found a Blue Discus type discus with bluish greenish turquoise stripes on the head, operculum and the dorsal, anal, pelvic fins. The only resemblance to Green Discus is a strong bluish green film on the whole body. The yellowish brown to light orange body has no red spots.

The best Green Discus is found in the drainage of Tefé and Juruá Rios. Rio Tefé Discus has light yellowish brown to orange body color. The numerous small and vivid red spots are either in rows or scattered all over the body. Besides Red Spotted Green, there is an abundance of Royal Green and some excellent Solid Green in this river.

Rio Juruá Discus also has a light yellowish brown or orange body but the red spots are scattered all over the body in abundance. Exceptional specimens having numerous small and vivid red spots on a light orange body are even more beautiful than the best from the Rio Tefé basin. There are also some big size Solid Green specimens living in Rio Juruá.

Green Discus from the Rio Japurá drainage has a smaller size and a longer body than those from the Tefé and Juruá regions. The basic body color is a light yellowish brown. Although the turquoise color is weak in most fishes, there are vivid red spots on the whole body.

Jutaí Discus is smaller than those from Tefé and Juruá regions. It has a light yellowish brown or pale orange body. Males have a lot of turquoise color on the body while females have a solid orange body. The red spots are present in both sexes but they are larger and are less numerous than those from the Juruá and Tefé Rios.

Green Discus from Rio Içá has a very pleasing light yellow body, not so much turquoise color and some small red spots; those from Rio Putumayo, the upper section of this river in Peru, have smaller sizes, a slightly darker body color, and a little more red spots.

Peruvian Green Discus

Discus from Rio Nanay has small scales and the red spots are scattered all over the body in a way that is quite similar to Tefé Red Spotted Green. There are also many Solid Green specimens living in this river. Quite a few of the Nanai Discus have a long streamer on the dorsal fin. The best Green Discus from the considerably longer Rio Napo has wide turquoise stripes and rows of beautiful red spots looking similar to Tefé Royal Green, yet most of them only have some red spots and a turquoise green film on the body.

Merits in Hybridization

Green Discus is best suited for the production of red spotted strains.