BOOK REVIEW “DAS GROSSE DISKUS BUCH” – Aquapress

BOOK REVIEW (at the moment available only in German)

Das Grosse Diskusbuch (= The Big Book of Discus)

Bernd Degen and 14 other authors

336 pages, hardcover, published in 2008 by

bede-verlag GmbH, D-94239 Ruhmannsfelden, Germany

ISBN: 978-3-89860-159-7

Euro 29.80 (Germany), Euro 30.70 (Austria)

Another Discus book from bede-verlag, and one can only ask, “Why?” Apparently, to get there before a recently very successful, and really large Discus book, based on genuine knowledge and practical experience, and being published in two volumes by another publishing company (the first, really large volume is already almost sold out). Even the format and the headings to some chapters are almost identical with the already-published Volume 1 and the forthcoming Volume 2. Although the publisher cannot have the slightly idea of the content of Volume 2.
But to the book itself: it begins with Geschichte der Entdeckung (= History of Discovery), which has been described hundreds of times but nevertheless the author has got it wrong, as it is not the Heckel Discus that was known as the Pompadour in the USA and elsewhere, but the Brown Discus. A lot is known about the early breeding of discus, but not by the author of this chapter, and he is also unaware that the first regular importations of Discus didn’t begin until the middle of the 1960s. And that no Discus has ever been caught in the mouth of the Rio Branco. He also appears never to have visited, and/or researched, the Rio Negro, as there is practically no difference in the water conditions cited from the Heckel Discus collecting site to Manaus, and there is no white water in the vicinity of Manaus. Moreover the boom in wild-caught Discus first began in the second half of the 1960s (there were practically no captive-bred stocks then) and not later as stated; but then the author was not involved with Discus back then.
Under Klassifizierung der Diskusfische (= Classification of Discus) it gets even worse. This appears to have been written by somebody with no idea of taxonomy and who has misunderstood the scientific work. Here are just a few of the mistakes:
1. There are no Discus in the Amazon river itself;
2. The “experts” are not at odds over the number of species that exist, that was

resolved in the 2007 revision and also noted by Eschmeyer, (2008) and the only

questions at present are in the view of the author, not in science or taxonomy.
3. Pellegrin did not erect any genus in 1904 – that was done by Heckel in 1840 –

or describe any species. Pellegrin in fact simply described a variant, which he

named S. discus var. aequifasciata var. nov. (and note, not aequifasciatus, that

came much later).
4. The “Review” published by L. P. Schultz in 1960 – with three subspecies and not

two as stated – remained valid only until 1986 (and not 2005 as stated) when

Kullander synonymised all the subspecies.
5. A so-called “classic” division of the wild varieties exists only among Discus

enthusiasts, not in science, and normally comprises Brown, Blue, Green, and

Heckel Discus. The “classic” division given here exists only in this book (and

maybe others from bede-verlag) and in the heads of those with no knowledge

of the scientific facts.
6. There are also incorrect data cited regarding Symphysodon discus: eg Natterer

first reached Amazonia in 1830 (not 1820); S. discus is not named after its first

describer but in reference to its form; to date there is no evidence of the

occurrence of a Blue-Headed Heckel Discus in the Rio Jauaperi; there are no

S. discus in the Lago Nhamundá.
7. It was not Axelrod that collected Symphysodon willischwartzi (since 1986 a

synonym of S. discus), but a caboclo in the employ of Willi Schwartz, and the

type has been examined (by Kullander) and identified as indisputably S. discus

Heckel, 1840, and is neither a natural hybrid nor a subspecies. In addition the

Discus pictured on page 11 (below) has nothing to do with the variant formerly

known as S. discus willischwartzi Burgess, 1981. The photo shows a S. haraldi,

the so-called “classic” Blue Discus.
8. In addition the description of Symphysodon aequifasciatus axelrodi Schultz, 1960

(= a synonym of S. haraldi) contains a number of errors: the ichthyologist Schultz

(the describer), who named the subspecies in honour of Axelrod, was never in

Amazonia; Axelrod was in Amazonia for the first time in his life in 1959 and not

“many years earlier”; it was not Axelrod who discovered the Cardinal Tetra, but

H. Sioli (and never collected it, as he obtained the Cardinal Tetra from a pet shop

in New Jersey); Axelrod was not one of the leading collectors for the aquarium

hobby (nor involved in a collection) – that honour goes to W. Pretorius,

R. Wandurraga, F. Cochu, A. Bleher, W. Schwartz, inter alia; there is no

Curipera Discus.
9. Under Symphysodon aequifasciatus haraldi Schultz, 1960 (= S. haraldi) there

are again errors in the text, for example: the majority of Blue Discus do not

originate from the Purus, and Manacapuru is not on the Purus, but at the mouth

of the Rio Manacapuru – a very long way from the Rio Purus.
10. The text on Symphysodon aequifasciatus aequifasciatus Pellegrin, 1904

(= S. aequifasciatus) is particularly full of mistakes: there are solid-coloured

Greens in the Rio Tefé but none heavily marked with red dots – the latter are

caught mainly in the Lago Tefé, in the Jutai, Coari, and Japura regions; in the

Green Discus the vertical bars are not striking (and are never particularly

prominent, but almost always uniform, in S. aequifasciatus); Asian breeders

had obtained Tefé Discus by the end of the 1960s and not only 12 years ago;

Asian breeders have never crossed wild-caught Discus, it was the Germans

who did that and the Asian breeders then bought the Tefé crosses; so-called

“Royal Green” Discus have nothing in common with the “Royal Blue” Discus,

they simply have the red dots all over the body, sometimes arranged in the

form of stripes; scientists don’t divide the three species into Brown, Green,

or Blue, at most they suggest a “common name”.
11. Apparently the author also has his doubts (under: Erste Zweifel (= First Doubts)),

as not only are Green, Brown, and Blue not three species but only two

(S. aequifasciatus = Green; S. haraldi = Brown/ Blue), but also the three species

(S. discus, S. aequifasciatus, S. haraldi) are not prone to crossing, either in the wild

or in the aquarium. (That is, moreover, extensively documented scientifically.)
12. After summarising the work of Kullander, inter alia, the author next mentions the

Arbeit von Ready, Ferreira & Kullander, 2006 (= The work of Ready, Ferreira &

Kullander, 2006). But he has also (apparently) not actually read that work, as it too

lists three species, as Géry & Bleher had already done in 2004. In addition he has

apparently overlooked the fact that this work is based entirely on genetic and not

on morphological results. Only the red spots in the third species, which they call

S. tarzoo, are mentioned. The fact that in Pellegrin’s day there was no formalin and

the specimens were stored in alcohol again speaks of ignorance.
13. In addition, under the heading Symphysodon aequifasciatus tarzoo (which Ready

et al. list as S. tarzoo, and merely suggest this name, not scientifically describing it)

there are again considerable deficiencies: the publication where the article by Lyons

with the “unofficial name” Symphysodon Discus Tarzoo appeared, is dated 1960 and

not 1959; in Bleher et al., 2007 it is clearly stated on page 140 (several times) that

the publication dated 1960 supposedly appeared on 28th November 1959 (quite

correctly cited and not read by the author) and in science it is the date of

publication that is critical.
14. The author’s comments on the 2007 revision by Bleher, Stölting, Salzburger &

Meyer are incorrect and full of mistakes: he overlooks the fact that the locations

used in this work lie far further apart than those in all other genetic works; that

the “assertion by Bleher” that there are three species is something that has

been known since the beginning of the century and published since 2004; that

Prof. Axel Meyer, a geneticist renowned worldwide, never made the statements

attributed to him in the form published here, nor was permission given to quote

him (there may be action as a result – pers. comm.); there was never any

question of designating a holotype, as the time for that was long past, it was

only the designation of a lectotype and paralectotype for S. aequifasciatus that

was stated to be urgently necessary back in 2004; that the specific taxon tarzoo

has never – to the present day – been described anywhere (and hence is a

nomen nudum); that at the time of the description of aequifasciata by Pellegrin

1904 what is now Tefé was still spelt Teffé and hence published thus (as in the

original description – another “oversight” on the part of the author); that the

publication by Géry (not Gery´) & Bleher 2004 is correct and that the book

Blehers Discus Volume 1 appeared at the end of 2005 and was generally

available at the beginning of 2006 and that the author himself ordered 7

copies on 3.10.2004 and received them on 17.05.2006; that the work of

Ready et al. wasn’t published until 1st December 2006 (however you look

at it, about a year later than Blehers Discus Volume 1); that Géry (not Gery´)

& Bleher never designated a holotype, but, as already mentioned, a

lectotype and paralectotype, and not purportedly, but actually, published; that

the types illustrated are not “purported”!, but the actual syntypes of Pellegrin

in the MNHN, all with their original numbers (attached to each specimen);

that the red dots are visible (apparently the author has poor eyesight, which

may explain why he keeps talking about a holotype that never existed in this

instance, no holotype was designated back then for aequifasciata – now

aequifasciatus – so there can never be one as one was never designated,

only the syntypes of Pellegrin and the lectotype and paralectotype of Géry

& Bleher); and he has also failed to notice that according to the ICZN

(International Code of Zoological Nomenclature) only three species are

currently valid, and they are S. discus Heckel, 1940, S. aequifasciatus

Pellegrin, 1904, and S. haraldi Schultz, 1960. Even the promised “further

works” referred to, which is the recently published (2008) genetic paper,

made no difference. This genetic publication also recognises three

Symphysodon species.
15. The illustrations under Klassifizierung der Diskusfische (= Classification

of Discus) also contains some notable errors: page 20 (below left) is not a

classic Heckel type but a cross – S. haraldi x S. discus – by Willi Brockskothen;

there is no Heckel Discus to be seen on page 21, either above left or above

right – both are Blue Discus (= S. haraldi); on pages 22 and 23 there are Brown

Discus with incorrect locality data such as Curipera and Mata Limpa (they don’t

exist except in the trade), likewise on page 27; on page 24 an Asian tank-bred

is shown as a Tefé Discus (above right), and page 25 (below left) is not a solid

       Green Discus.
There are also major errors, erroneous and misleading statements, incorrect maps and data to be found under Fanggebiete (= Collecting locations): at its source the Amazon is called the Nevado Mismi and not the Gayco; the Amazon system comprises more than 100,000 rivers, not 1000; visibility in whitewater is only around 5 cm, not half a metre; the photo on page 28 of the confluence is the wrong way round; page 29 (11) does not show Jatapu Discus, they do not occur there; Hustinx calls the Green Discus S. aequifasciatus aequifasciatus (?) and says that fishing takes place by night at high water? (to date nobody was able to do so when everything is under water); the map on page 31 doesn’t show the distribution of Discus, but the lower Amazon from Manaus to its mouth?; he was in Nhamundá but doesn’t know how it is spelt; and according to Hustinx the Solimoes (= Solimões) flows in the direction of Peru in order to become the Peruvian Amazon there (p. 32) – so has the Amazon turned around so it now flows west, likewise the Rio Japura (=Japurá)?; on page 33 there is a picture of a “Tefé Discus from the Japura”?; and on page 34 there is Crenicichla temensis – a new species, or Cichla temensis?
Diskusfang in Amazonien (= Discus collecting in Amazonia): on page 36 there is a Discus caught at Curipera? (problem: the lake doesn’t exist); according to Hustinx and Kleykers the dry season supposedly extends from August to February, but where? (Amazonia is larger than Europe); likewise on page 38 Discus are supposedly collected in November in most places (certainly never in the lower Amazon region); on page 40 the “Policia militar” are said to make checks – this has never been the case in Brazil, it is the Policia Federal; on page 41 there is yet another new species: Cichlasoma ocelaris (is this the original description? Or Cichla ocellaris?); “Project Piaba” was never recognised by IBAMA, and ceased to exist long since; and positive lists are not “handed out” but can be downloaded from the IBAMA website; freshwater rays have never been food-fishes, either in Brazil or anywhere else in South America; there is no list of species that can no longer be exported, just a positive list.
There are again incorrect statements under Vom Fang bis zum Exporteur (= From collector to exporter), such as: the nets used for Cardinal Tetras are “also” used for collecting Discus?; fish collectors in Amazonia do not plant bananas (but they do); on page 43 we learn that Green Discus grow on in a pH of 7, but where? – certainly not in Amazonia; on page 47 that the planes are not pressurised (and how do we survive that?); on page 48 it says that in Brazil (a large country) wonderful, pleasant, tropical temperatures prevail year-round and it rains hard now and then, and that the coast enjoys a mild climate with winter temperatures – but where? (the coast is around 4000 km long from north to south); that during a so-called Friagem (drop of temperature) the temperature supposedly drops to 10 °C (none of the caboclos would survive that, let alone the wildlife); that plastic boxes are forever turning up in the forests of Brazil – out of thin air?
Again there are many inaccuracies under Importvorbereitungen (= Preparation for importation), for example: on page 54 it says that maize flour (to date totally unknown in Amazonia) can fall into the Discus container?; on page 57 we learn that the main collecting season extends from October to March (when everything is under water)?; on page 60 that 18 years ago Discus were not fed in the holding tanks and that it was Mr Degen who first introduced the exporters to the concept? (so just how did Discus survive between the end of the 1950s and his visit in 1990?); and that oxygen is more important to Discus than water (and live on air?); on page 69 we are again told that Heckel Discus occur in the Jatapu? (previously it was in the Uatumã); on page 70 the reflection of the camera flash in the eye of the Discus is described as typical clouding (above left); and that in Heckel Discus the greatest losses occur between capture and the domestic aquarium? and that freshly imported fishes always have problems (= unknown among exporters and importers during the last 50 years); and finally, on page 72 we learn that we have all repeatedly got it wrong in the past: the transportation water doesn’t need to be equalised with the aquarium water; that temperature shock has no ill-effects on the fish, nor does a change in conductivity!
Under Wichtige Hinweise beim Kauf von Diskusfischen (= Important tips on purchasing Discus) we first of all learn that Discus are belligerent creatures, ie aggressive fishes. Unlike some other cichlids they do not have striking spots or other types of markings on the fins or on the opercula, sometimes designed to attract attention away from particularly vulnerable parts of the body and in other cases to make the body outline look larger, and are thus apparently defenceless fishes (we can only wonder how people nevertheless manage to keep such “aggressive” Discus). And there is more: in the wild the appeasement behaviour of the weaker, subordinate individual as a rule inhibits the aggression of superior, dominant Discus, while sometimes the subordinate fish avoids further attack by flight. The corollary is that under such – too restricted – conditions the subordinate fish may be killed, although this would not happen in the wild. We also learn that the author has conducted underwater behavioural studies in Amazonia. But it gets worse still: we learn that after an order of rank has been established the relationships among the Discus will become stable, but thereafter any interference by the aquarist – for example the addition of new fishes or alterations to the décor – can have catastrophic consequences and start the Discus shredding one another again. And the worst thing one can possibly do is to perform a water change, as “a water change causes the aggression to escalate…”. So, no more water changes! (Luckily one photo is captioned to the effect that overall Discus are not particularly belligerent.)
Furthermore we learn that “adult” Discus (so how large is “adult”?) can supposedly match their colours to one another; that Discus that become ill during the growth phase tend to remain stunted or develop an unattractive elongated form (without mentioning that this might be something to do with diet); we learn that in Discus the pupil of the eye is black and but red in an albino (of course, none of us knew that); that one can tell from the eyes whether the fish is healthy (and thus recognise any disease – just look at the eyes); however, the eyes should be without defect and dark, even black eyes indicate disease” (but the pupil is always black!)! This begs the question: what colour should the eyes be, black or not black? But luckily we are told that nowadays there are attractive Albino Discus (what about those we had around 40 years ago?). Heckel Discus should usually have amber-coloured eyes (Mr Göbel says that all Heckel Discus must have red eyes) and that Green Discus usually have red eyes (and you have only to look at a few hundred Discus to realise that none of these statements is accurate). In the section on Löcher im Kopfpartie (= Holes in the head region) we learn that the dreaded Hole-in-Head disease is characterised by rather uniformly shaped, small holes, but on page 86 the holes are quite irregular (likewise on pages 288 and 289), and that it is difficult to cure? (but that is not what Untergasser says later).
Under Kiemen- und Streifenfehler (Gill and stripe defects) we learn that Discus with opercular defects should not be used for breeding (why? hardly heritable!) and that stripe defects are more frequently to be seen (which also goes to show that the author can’t have seen many Discus). We also learn that only “normal” Discus have nine dark vertical bars and only the new cultivated forms from South-East Asia have thirteen, fourteen, or even fifteen such bars (it would appear that the author has not read any of the scientific works, looked at any publications on wild-caught Discus, or consulted other breeders).
Under Ausgezogene Flossen (= Elongated fins) we are told that only captive-bred Discus have long fins and fin extensions, with good feeding supposedly the main reason for this, and that because in the wild Discus live on a subsistence diet their fins don’t grow. Thus the writer is assuming that there are no prolonged fins in the wild (and while science can’t help in this instance, our eyes most certainly can). Another statement born of ignorance. Hardly any breeder has so far managed to produce fins as prolonged as those that can occur in Discus in the wild (see the bibliography below – there is none in the Grosse Diskusbuch). In addition Discus supposedly spawn earlier in the aquarium – sexually mature at 10 months – than in the wild (although they spawn there at 8-9 months old, as during the high-water period they grow more rapidly than in the aquarium, because of the abundant food supply).
Under Pflege im Aquarium und Streßfaktoren (=Aquarium maintenance and stress factors) we are again not told how large an “adult” Discus should be (in order to provide it with the prescribed amount of water (60 l = 1 Discus?), but we are informed in words and pictures that when Discus sit beneath a piece of wood they are stressed. So, we should throw away all our bogwood and burn down (or clear-fell) the whole of Amazonia, as if what the author says is true then all the Discus in the wild are stressed 24 hours a day (and we don’t want that, do we?). And please don’t use driftwood, as then your Discus won’t be stressed and can “swim majestically through the aquarium”, for which – we are told – plants are the best decor. We are also specifically told not to switch the light off suddenly in the evening as then the Discus won’t be able to prepare for night and will carry on wandering around. It is even suggested that Discus should be provided with a night-light, as then if they spawn or are leading young, the parents will be able to look after their offspring at night without problem…? (Are there night-lights in the wild? No doubt this is why more and more hydro-electric dams are continually being constructed in Amazonia – so that the Discus won’t have to live without light!)
In the section on behaviour under Geeignete Mitbewohner (=Suitable tank mates) we learn that matters are completely different in the wild to in our aquaria (now who would have guessed that?). There is speculation on who hunts whom in Amazonia (because the author was never there or hasn’t done his homework); it is stated that Discus eat other fishes (but they don’t in the wild); and that until recently tetras weren’t considered as tankmates (which means that all the Cardinals, Rummy-Noses, and other small characins that were swimming around in Discus communities over 40 years ago weren’t tetras – what were they, then?). Apparently it was not until the end of the 90s that aquarists started to wonder whether Discus and tetras might not be kept together without major problems. Either that was when the writer was born, or he has again failed to do his homework. We learn that hatchetfishes have upward-pointing mouths and use their eyes to observe life outside the water (not noticing the predator approaching from below…), and hence are ideal (?). But that isn’t all: they can also jump 3 to 5 m across the water’s surface (so how come there are still any left in aquaria?). The author has quite simply never observed these fishes or taken any note of any of the publications and documentaries of the BBC, Stan Weitzman, and others, who demonstrated decades ago that they don’t do that at all … (they can only hop upwards, as does the African Butterflyfish, in order to evade an approaching enemy). Three genera of the family Gasteropelecidae are supposedly of interest to the aquarist (but there are only three). We learn all sorts of new information, such as: the Silver Dollars are “plant-eating Piranhas”; that Anostomus and Leporinus sometimes attack Discus and that Cardinal tetras may be eaten if not full-grown (and how big is that?).
We are shown Pterophyllum altum (but they aren’t that species), which don’t occur with Discus, any more than do African dwarf cichlids and fighting fishes, let alone rainbowfishes, or cyprinids such as Rasbora, Danio, Puntius, and Trigonostigma, or Aphyosemion species. And most definitely not Swordtails or Platies. How anyone can recommend such fishes as tankmates for a Discus aquarium is really questionable…
Then some of so-called L-number catfishes are recommended that will quite definitely cause harm to Discus and can even kill them, for example the Hypostomus spp. illustrated (and there is plenty of literature to this effect). In addition, all L-number catfishes have accessory breathing, but this too has been overlooked…
Under Einrichtung eines Wohnzimmerschauaquariums (=Setting up a show tank for the living-room) (what about the office or elsewhere?) we learn that Discus are almost always kept in bare tanks (apparently the writer has never looked on the Internet, or otherwise done his homework) and an attractive planted aquarium is recommended (biotope-correct maintenance?). Carbon dioxide systems are recommended (yet elsewhere in this book it is stated that the gas is toxic to Discus, and that writer is not entirely wrong). Under points to note we learn that the most important rule is never to introduce small Discus as that doesn’t work! So one should buy only Discus of 12 cm upwards (?), and it is even better if they are somewhat larger (???), as at a year old they have a body size of 14-16 cm (that means they are 18-20 cm with fins, a size that not even the best breeder in Taiwan can achieve in a year). But it gets even better: a further important piece of advice is to completely do away with natural wood. In other words remove all wood and boycott the worldwide trade in wood for aquaria. And in conclusion it is again stated that these are the two most important rules. (I just hope that Discus merchants, breeders, wholesalers, importers, and pet-trade retailers don’t read these two most important rules…).
Then, under Richtiger Standort (=Correct sitting) there are photos of nine display aquaria (spread over six pages) without a single Discus in any of them. Then under Die richtigen Pflanzen (The right plants) (so are there also wrong plants, or are plastic plants meant?) we are told that plants will effect a dramatic change. And also (p. 136) that straight pieces of wood are splendid decorative material“ (???). And again, on page 137, that Discus are particularly fond of sitting under wood (so now they are no longer stressed or near to death!). In fact the praises of wood are sung here and we are told that it is unsatisfactory if the Discus sit hiding behind plants (but previously a display aquarium full of plants was commended and regarded as one of the most important criteria, and we have only just learned that they will effect a dramatic change – what next?). And carbon dioxide is again recommended, and again on pages 144-145, so that the plants will grow vigorously (the Discus are thus not the main criterion). On pages 150-151 our attention is drawn to “fewer plants” and remembering to install a night-light“ (just like in the wild…) and the reflection of the camera flash in the eyes of a number of attractive Heckel Discus is again interpreted as slight clouding. That apart, there are a whole series of photos of decorated aquaria coarse gravel and other aquarium decor potentially harmful to Discus. Next we are told that a biotope aquarium is preferable, but at the same time somewhat boring. Hence: plants are back in. We are also told that it is difficult to say what a biotope aquarium should look like (although there are around 13 000 pages with examples, to be found at google.com), and first of all we must find out what the biotope looks like, which isn’t known (one wonders increasingly just what, if anything, the writer does know?). And again we are told that were we to construct a biotope aquarium then it would be a miserable affair (at least we learn that the wild is “miserable”, but then I have to ask myself, why are we seeking to conserve it?). But fine sand is good. We are shown a “biotope aquarium” full of Vallisneria (?) and are told that it is OK to take the liberty of including occasional plants that aren’t native to Amazonia (?).
Professionelle Hälterungsanlage (= Professional establishments) and breeding in South-East Asia are documented, and on page 157 (above) there are two photos that supposedly show a “new colour pattern” in Discus – absolutely identical to variants that Hohman bred in Bad Schwalbach back in the 1970s (see Bleher & Göbel, 1992), and it was also there that the first Pigeon Blood Discus was pictured and not in Degen’s Diskusfische Asiens, published in 1994, by when it was already “old hat”.
Thereafter there are 22 pages, text and large photos, of just a single major establishment in Europe, followed by (again) major establishments in South-East Asia, and we are told that the latter differ in some respects from the European. We get 14 pages of mainly sharks, sewage, rubbish, arowanas, and brightly-coloured cichlid, with hardly a Discus in sight. And the arowanas include Osteoglossum ferreirai (Black Arowana), freshly imported from Amazonia, described as youngsters of the Asian Scleropages formosus.
There follow 16 pages on “the greatest breeding establishment in Europe”, that of Stendker, and then 10 pages on water as the life-element of Discus (and undoubtedly suitable for other life forms as well). This is without doubt a good list with lots of water data, but no Discus biotope and no test results for such. Just values for other natural biotopes. On the 8 pages with the title, Das richtige Futter (= The correct food) no distinction is made between wild Discus and cultivated forms (and the difference is considerable). And under Lieblingsfutter (=Favourite foods) we are told that almost all types of food are suitable (?).
There follow 34 pages on Erfolgreiche Zucht (= Successful breeding) and very large (often full-page), sometimes very beautiful photos (mainly by Horst Linke) and 18 pages on Künstliche Aufzucht (= Artificial rearing), again with copious full-page photos (to make the book thicker?). The following 28 pages on Gesunde Diskusfische (= Healthy Discus) consist of text and photos by Dieter Untergasser, presented to his usual high standard. Although mostly borrowed from his books Gesunde Diskusfische and Großcichliden Volumes 1 and 2, (also published by bede-verlag in 1991 and 1993) and Gesunde Aquarienfische (bede-verlag, 2002). The penultimate 4 pages of this chapter are devoted to the “parasite-free Discus”, a time-worn topic, and Untergasser’s bibliography (the only one in Das Grosse Diskusbuch). And I would rather not say anything here about the Medikamenten-Verabreichung nach Degen (= Administration of medications according to Degen), as that could well (and should) appear under the heading “Cruelty to animals”. It was 20 years ago, still is, and yet is here dished up yet again. Almost beyond belief.
In the chapter Klassische Diskusfarben (=Classic Discus colours) we learn that this is nothing to do with cultivated forms, but at the same time page 314 is devoted to photos of such forms. Next we learn that Jack Wattley supposedly bred the first turquoise (perhaps because Dr Schmidt-Focke is long gone?) and that this became known as the solid turquoise (that too originated from the Doctor). He (Jack) is supposedly one of the absolute pioneers (again undoubtedly because others are no longer alive). On page 315 the upper photo shows some Snake-Skin Discus, captioned as the first brilliant turquoise, a term that can at most be applied to the lower fish on this page. The fishes in the upper photo are Snake-Skins from Willi Brockskothen. We are told on this and page 316 that Discus breeding first took root in South-East Asia after 1985, or, according to Kuan Kuo Zin (from Taiwan), not until 1988 (that may have been the case in Taiwan), while Lo in Hong Kong and others who already had enormous breeding establishments 10 years earlier are completely overlooked (but there was no bede-verlag then and Mr Degen was publishing cookery books). But we learn that Degen was an important exporter and that German breeders were responsible for red-turquoise (two pages previously it was still Schmidt-Focke…).
Under Moderne Diskusfarben (= Modern Discus colours) a number of old acquaintances are portrayed as new colour variants (pp. 320-325) and some of the “modern” names listed, such as Blue Diamond, Pigeon Blood (both known since the beginning of the 1990s), Red Melon, Leopard Green (another new name for an old friend), Leopard Snake-Skin, San Merah (normally used of a completely different Discus), White Diamond or White Swan (whatever next? Normally just known as White, but Swan or Diamond sells better…).
Under Diskus im Zukunft (= Discus in the future) we learn that it all really started in earnest 20 years ago (although more Discus were being sold 30 years ago than 20 – or today – but remember, Mr Muddlehead was very young back then). Bewitchingly beautiful, light Discus are supposedly a new trend (but have been widespread in Asia for more than 10 years – and in demand only there). But he concludes it is not possible to make any definite forecast.
Under Diskus bei Championaten (= Discus at championships) we are told that colour and body size should be the main criteria (characteristics) of Discus for a championship show. Well, that explains why so much incorrect judging takes place at some championships (but it is the judges’ opinion that counts). I can only hope that these “main criteria” (colour and size) are not also applied in future to Miss Universe, to Koi or Goldfish, to Guppies or Swordtails. In addition we are told that a Discus should be not only large, but also at least 18 months old. Note that this means that attractive youngsters (less than 18 months old) will not be judged, no matter how beautiful they are. Perhaps it should be suggested to the Miss Universe Commission that no woman under 25 can qualify!
And there is even worse under the 15 Standardkategorien der internationalen Diskus-Shows (= 15 standard categories at international Discus shows) (hence not at championships, I hope). Here Red Turquoise are confused with Striped Turquoise (it seems the author doesn’t know which is which); Red Spotted and Snake-Skin are practically identical, likewise the AOV Spotted class (so how are breeders and enthusiasts supposed to recognise or differentiate them???); the category Golden is worse than illusory as there are as yet so few specimens; likewise White is not a category per se and Red Spotted still belongs in the AOV class. All that can be said about this classification and the accompanying illustrations is that it is pitiful and worse than confusing – as far from providing a standard as the Earth from the Moon…
Finally there is Diskus im Internet (= Discus on the Internet) with just a miserable two URLs (just the two that recommend Das Grosse Diskusbuch on their pages…), even though there are plenty of other very good ones, including German-based.
Summary: Don’t buy, a waste of around 30 Euros and not worth reading, apart from the few chapters mentioned, but even those tell us nothing new that hasn’t been written previously or better.

References:
Bleher, H., 1984. New Discus Strains From Dr. Eduard Schmidt-Focke. Tropical Fish Hobbyist, T.F.H. Publications, Inc. 32 (8): 8-47
Bleher, H., 1993a. DISCUS – Wild-caught and captive-bred forms (supplements). Aquaprint Verlags GmbH, Germany, 48 pp.
Bleher, H., 1994b. Discus. aqua geõgraphia, 8: 80-83.
Bleher, H., 1994/5. DISCUS – Wild-caught and captive-bred forms (supplements). Aquapress, Italy, 48 pp.
Bleher, H., 1996/7. DISCUS – Wild-caught and captive-bred forms (supplements). Aquapress, Italy, 48 pp.
Bleher, H., 1998b. DISCUS – Wild-caught and captive-bred forms (supplements). Aquapress, Italy, 48 pp.
Bleher, H., 1998c. Dr. Eduard Schmidt-Focke – A Life Devoted To Discus. aqua geõgraphia, 17: 56-68.
Bleher, H., 1998. Dr. Eduard Schmidt-Focke – Ein Leben für den Diskus. aqua geographia, 17: 56-68.
Bleher, H., 1999/2000. DISCUS – Wild-caught and captive-bred forms (supplements). Aquapress, Italy, 48 pp.
Bleher, H., 2003b. Nhamundá. aqua geõgraphia, 24: 54-56.
Bleher, H. & Göbel, M. 1992. DISCUS – Wild-caught and captive-bred forms. Aquaprint Verlags GmbH, Germany, 148 pp.
Bleher, H. & Linke, H. 1991a. World of Discus – King of the Amazon – History and Care. Aquaprint Video Production, Germany.
Bleher, H., Stölting K. N., Salzburger, W. & Meyer, A. 2007. Revision of the Genus Symphysodon Heckel, 1840. aqua International Journal of Ichthyology, 12 (4): 133-174.
Burgess, W. E. 1981. 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. 29 (7): 32-42.
Eschmeyer, W. California Academy of Science Ichthyology, Catalogue of Fishes, on-line version, updated 19 September 2008.
http://research.calacademy.org/research/ichthyology/catalog/fishcatmain.asp

Farias, I. P. & Hrbek, T. 2008. Patterns of diversification in the discus fishes (Symphysodon spp. Cichlidae) of the Amazon basin, Molecular Phylogenetics and Evolution (2008), doi: 10.1016/j.ympev.2008.05.033.
Geisler, R. & Stawikowski, R. 1994. Harald Sioli und die Limnologie Amazoniens. Amazonas, Datz Sonderheft. April 1994: 10-14.
Géry, J. & Bleher, H. 2004. Kommentar zur Taxonomie I. Anmerkungen zu den Typuslokalitäten der Arten und Unterarten der Gattung Symphysodon Heckel, in Bleher, H. 2006, Bleher’s Discus. Aquapress Publishers, Italy, pp. 135-136.
Géry, J. & Bleher, H. 2006. Comments on Taxonomy I. Remarks on the type localities of the species and subspecies of the genus Symphysodon Heckel, in Bleher, H. 2006, Bleher’s Discus. Aquapress Publishers, Italy, pp. 135-136.
Goulding, M. 1980. The fishes and the forest: Explorations in Amazonian Natural History. University of California Press, Berkeley, CA, USA, 280 pp.
Heckel, J. 1840. Johann Natterer’s neue Flussfische Brasilien’s nach den Beobachtungen und Mittheilungen des Entdeckers beschrieben. (Erste Abtheilung, die Labroiden.) Annalen des Wiener Museums für Naturgeschichte 2: 327-470.
Innes, W.T. 1933. New Importations, The Crested Cichlid (Symphysoson discus). The Aquarium, Innes Publishing Co. 2 (5): 327-328.
Innes, W. T. 1935. Symphysodon discus (Heckel) – The Aristocrat of the Aquarium. The Aquarium. October 1935, 119-122.
Junk, W. J. (Ed.), 1997. The Central Amazon Floodplain. Ecology of a Pulsing System. Ecological Studies. Springer-Verlag, Berlin & Heidelberg, 525 pp.
Köhler, H. 2008. Asiatische Diskusfarbschläge: Revolution in der Diskuszucht. Amazonas – Süßwsseraquaristik-Fachmagazin, 20: 16-28.
Kullander, S. O. 1986. Cichlid fishes of the Amazon River drainage of Peru. Swedish Museum of Natural History. Stockholm, Sweden. 431 pp.
Kullander, S. O. 1996. Eine weitere Übersicht der Diskusfische, Gattung Symphysodon Heckel. DATZ Sonderheft Diskus (1996): 10-19.
Lyons, E. 1960. Symphysodon discus Tarzoo. New Blue Discus Electrify Aquarium World! Tropicals Magazine Holiday Issue –1960, 4 (3): Cover, 6-8, 10.
Pellegrin, J. 1904. Contribution à l’étude anatomique, biologique et taxinomique des Poissons de la famille des Cichlidés. Mémoirs de la Société zoologique de France 16: 41-399.
Ready, J. S, Ferreira, E. J. G. & Kullander, S. O. 2006. Discus fishes: mitrochondrial DNA evidence for a phylogeographic barrier in the Amazonian genus Symphysodon (Teleostei: Cichlidae). Journal of Fish Biology 69: 200-210.
Schultz, L. P. 1960. A review of the Pompadour or Discus fishes, genus Symphysodon of South America. Tropical Fish Hobbyist. T.F.H. Publications, Inc. 8 (10): 5-17.
Schultz, L. P. 1961. Haben sie einen echten Diskusfisch? Tropische Fische, T.F.H. Publications, Inc., Europa-Vertrieb, München. (April 1961): 148-157.