Can I cross different types of goldfish

Questions about goldfish

Dr. E .:

(Kraepelin, 1921)

Some common questions have already been answered in the text on various pages of this website. For many questions, however, I have not yet worked out a text in the context of which they can be clarified; sometimes some questions cannot be integrated into a larger text. It is therefore worth taking a look at this collection of questions, which actually has a direct reference to the currently neglected chapter of biology.




!The age usually reached by goldfish is around one to one and a half years: They are sold as summer fish, and in the care of their "keepers" they survive for another six months ...

Basically, goldfish live to be relatively old. The simple (normal) goldfish live to be around twenty-five years old; Forty years has been guaranteed several times as the maximum age in Europe, Chinese enthusiasts even report fifty-year-old goldfish, which has not been proven.
However, one should not orientate oneself to such record holders: Even if people keep getting significantly older than a hundred years, this is not the rule.

Specifying a lifespan for goldfish is difficult for a number of reasons:

Some authors (e.g. Pénzes & Tölg, 1993) even write of only around seven years of age, and many goldfish keepers do not even manage to let their animals grow older than five years. If you look at the posture recommendations made by such authors, there is a lot to criticize there (goldfish bowls, etc.). The short lifespan that many goldfish achieve can often be attributed to poor keeping conditions. Fish that are permanently damaged by poor breeding and rearing conditions as well as unfavorable import conditions also have a shorter life expectancy.

Especially in discussions among aquarists, “best conditions” are sometimes blamed for fish to reach old age.
What are “best conditions”? The well-known record holders (Tish and Goldie; see All sorts: Famous Goldfish) did not live under conditions that, with a little specialist knowledge, can be described as species-appropriate. In addition to a good genetic predisposition, other factors also played a role here: economical feeding and the avoidance of any activities that cause depletion of the fish's reserves. Killi breeders reported in a forum that those fish that are used for breeding regularly die earlier than those kept in isolation that were not exposed to the stress and exhaustion during reproduction. So it can be said that even non-natural conditions can increase the lifespan. Zoo animals usually get older than their wild counterparts (regardless of diseases and predators).

Taking these aspects into account, the 25 years mentioned are, in my opinion, a realistic age expectation for goldfish. A few more years may be possible.
High-breeding forms usually do not get that old (in this they do not differ from pure-bred forms of other domesticated animal species), the usual information is from ten to fifteen years. In my opinion, however, a significant shortfall of ten years indicates inadequate conditions and / or poor disposition of the fish.

Two normal goldfish, which I kept as a child under unfavorable conditions, later as a teenager under gradually improved conditions in a tank that was much too small, lived to be twelve years old; one of them died of an abdominal tumor. Of my current goldfish, the oldest is now almost fourteen years old.

! Neither the color nor the size of the fish allow a reliable conclusion about the age. The only sure age determination is the microscopic examination of scales, which have concentric lines similar to the annual rings of trees, the number of which corresponds to the age. The mechanism is comparable: in the cooler and less nourishing winter, less growth takes place than in summer. For this reason, it is more difficult to determine the age based on the scales in aquarium fish, which usually live under constant conditions. Since individual scales grow back when they are lost, several scales must also be examined.


! The achievable size of goldfish in the aquarium is approx. 30 cm under appropriate conditions. This also applies to relatively small aquariums; I've seen goldfish myself that reached 28 and 32 cm in a 200 liter aquarium! In Central Europe, up to 35 cm are not uncommon in garden ponds. In Indonesia, goldfish kept as food fish are over 40 cm tall (Ott & Dettmers, 2004); American literature states that the attainable size is 16 to 20 inches (40 to over 50 cm) (Innes, 1917, Mertlich, 1988 et al.).

In the aquarium goldfish are sometimes only 12 to 15 cm long; The causes are manifold. It is a common misconception that fish adapt to tank size in their growth (and stay small in a small tank just because the tank is small)! No fish chooses it Follow Oskar Matzerath and stop growing. Tests by the Federal Research Institute for Fisheries have shown that carp can grow very large even in very small pools. It appears that inhibitors play a role here, which are released by the fish into the water and delay growth when they accumulate in the water.
Such miserable growth is sometimes referred to (especially in Internet discussions) as 'pathological' by zealous animal rights activists without knowing the exact context, which it is clearly not. I doubt whether this stunted growth alone constitutes cruelty to animals. I do not doubt that it is usually an indication of keeping conditions in need of improvement (tank size, feed quality and quantity, water quality, water temperature, stress, etc.), but I do not want to judge too strictly. Goldfish that remain small remind me of stone crucians (see Biology I: Description of goldfish and close relatives).

There are no generally small goldfish cultivated forms! Some zoo dealers claim to ignorant buyers that certain "veil tails" are one; even the alleged sales offer has already been reported in forums! Such statements are customer stupid nonsense are based on ignorance of the seller. Some veil cultivars (such as Orandas and Ryukins) become very large. There are no “races” that remain small. Only a few high-bred lines that can hardly be preserved in Europe remain relatively small due to strong inbreeding.

Fish grow their entire life, but at different speeds: very quickly in their youth, usually so slowly in old age that it is hardly noticeable.
A goldfish that has lived in stunted conditions for years is unlikely to grow to full size in a very large tank or pond. Our own observations in this regard show that six-year-old animals, which previously had no longer grown visibly, after relocating show clearly recognizable, but still slow growth.


! As mentioned in the previous question, fish - unlike mammals - grow their entire life. In addition, the growth of fish is influenced by significantly more factors than in mammals. While fish under conditions that are equivalent to their natural life usually have reached their "final size" within a certain (species-dependent) time, from which growth is greatly slowed down and hardly measurable, different conditions can inhibit or inhibit growth in pond fish and especially in aquarium fish - have a delaying effect.
This is with the genus Carassius particularly pronounced (see also the information on stone crucian carp under Biology I: Description of goldfish and close relatives). Many old aquarium goldfish measured only 10 to 15 cm even at the age of 20 and more, while some pond inhabitants can reach 25 to over 30 cm in the course of three to five years. If the conditions change, fish that have remained small can, under certain circumstances, clearly increase in size even after they are several years old. Sometimes they don't either. Our own experience currently indicates that the food supply is very important during a certain early phase of growth. An older goldfish cannot make up for a corresponding shortage during this time, even under the best conditions. This seems to me to be the case for a great many commercially available fish.
So you can neither make a temporal nor a size-related statement when a goldfish has grown up. The achievable size is approx. 30 cm (see above); but whether and when it reaches this size is individually different.


!Just a: Carassius auratus is the only kind.
There are, however, many cultivated forms of this species; and the answer to the question of how many cultivated forms there are (sometimes also varieties, "varieties" or incorrectly called "races") cannot be answered.
The Federation of British Aquatic Societies (FBAS) has set 17 standards. However, there are far more cultivated forms, and through crossings and new characteristics there is an unmanageable number of intermediate forms. In China there are said to be 300 to 450 different forms.
More on this topic in the chapter on cultivated forms.


! The color pigments of the goldfish lie in different skin layers and change depending on the breed / mutation and age. When hatching, the young larvae are initially transparent to dark gray-green, which corresponds to the color of the wild form. The fry then usually (not always) develop their camouflaging black youth color very soon. These pigments, which are located in the outer layers, are broken down starting at the belly, and the red pigment layer underneath becomes visible. Finally the back and the fins are black. Instead of the gradual disappearance of the black color towards the back, it can also happen that the whole fish first turns bronze and then red. If the red pigment layer is completely or partially absent (in the case of partial absence, more on the underside), the fish appears white. A white or red and white (Sarasa) goldfish is this i. d. Usually immediately after the youthful change of color: red and white layers are visible at the same time.
These relationships do not apply to the brightly spotted calico colorations (e.g. Shubunkin); these are pronounced from the beginning (even if only faint and pale at the beginning).

Goldfish can bleach, so it is reported from time to time about old fish; recently also increasingly of young fish. While the former is a phenomenon of aging, the latter is more likely to be attributed to careless breeding: it is evident that more and more animals are establishing themselves in the breeding lines, which inherit only a low “color stability”. So it can be perfectly normal for a goldfish to discolor or turn white. This is particularly common with the calico-colored varieties (Shubunkin and others).

With Shubunkins and other calicos, the blue / black coloration can intensify when they are outdoors (in the pond). This could be due to the influence of UV radiation; I do not yet have precise information about the background.
In addition, some goldfish can spontaneously (?) Change color in the course of their life. To what extent such discoloration or discoloration are triggered by environmental conditions is difficult to assess. I am aware of a few such reports and no pattern can be discerned.
There are also cases where clearly unfavorable keeping conditions lead to discoloration: the fish fade or turn white. The occasions often seem banal (e.g. moving from a pond to an aquarium), but the fish in question do not seem to feel comfortable. Partial blackening caused by stress is also possible, it must be taken very seriously and slowly disappears again when you recover.
Black spots are also possible after skin injuries and / or drug treatments (which in turn can attack the skin): This black coloration is based on black pigment cells (melanophores) as a response to the leukine produced by the body (which stimulates cell growth). Comparable to the black coloration of young fish, this "healing black coloration" is not permanent, but will return to the normal red to white color of the fish over time.
Melanosarcomas as a cause of black spots are also possible: a type of skin cancer in which the melanophores develop excessively and thus lead to discoloration. These malignant growths are fatal but are rare.

! In this case a precise power of observation is required, because there are several possibilities here. The three most striking are briefly presented here:
White spot disease is a possible (dangerous) disease, but it can also be a spawning rash. Glochidia infestation is quite rare.

The White spot disease (also known as Ichthyophthiriasis or "Ichthyo" for short among aquarists) is from the ciliate Ichthyophthirius multifiliis evoked. It leads to white, semolina-like points that are scattered all over the body: initially only a few (often on the caudal fins), later more and more. The fish often rub against stones and plants. In this case, an increase in temperature and the addition of a drug containing malachite green oxalate as soon as possible (alternatively a salt cure) help. With regard to spreading resistant pathogens, the transfer method is highly recommended (e.g. described on Alternatives to chemotherapy at aquamax). Very helpful and well-founded information about Ichthyo can be found on Tobias Mösers Aquaristic pages. Also on Renate Husmann's side Fighting white dots effectively without medication (unfortunately the salt concentration specified is too low), sensible and helpful therapy methods can be found.

The Spawning rash on the other hand, forms during the spawning season (spring, summer) in sexually mature male goldfish that are in the mood for mating. The small, hard white-yellowish raised points are limited exclusively to the gill covers and their immediate surroundings (head, pectoral fins). Often the male in question drives a female through the pelvis. Anyone who notices something like this in their fish has discovered at least one clear (albeit temporary) gender characteristic in the goldfish, which are otherwise very difficult to distinguish. This spawning rash is nothing to worry about.

The so-called Glochidia are the parasitic larvae of river and pond mussels. The origin and habitat of the fish therefore always play a role in the assessment. Glochidia, for example, will only appear in a shell-less aquarium if the fish have been re-introduced from the field. If the white points are slightly yellowish, triangular on closer inspection, exactly the same size (Ichthyo points are slightly variable in size) and mainly located on the fins (and - less visible - on the gills), then it is glochidia infestation . Glochidia are also characterized by the fact that they appear, go through their development (depending on the type and temperature, 14 days to 5 months) and then fall off. The glochidia infestation is therefore a temporary matter from which the fish, if they are not weakened by too many mussel larvae, recover well if they are in good physical shape. Therefore, pay attention to particularly good housing conditions. However, if the glochidia are sitting en masse on the gills, suffocation can occur. Glochidia that have once attached themselves to the fish are not contagious in fish-to-fish contact.


! Normally, apart from the occasional feed envy, goldfish are peaceful with one another. If, however, one, two or three fish drive another one wild and try to constrict it, it is very likely that it is a matter of males (Milchner) willing to mate who want to induce a female (Rogner) to lay eggs. Milk farmers can also chase each other as “foreplay”. The males can then also be recognized very well by their spawning rash (see previous question). If the tank is large enough, it shouldn't be a big problem even for a female unwilling to spawn, so there really isn't any cause for concern. However, there should be an appropriate gender ratio: ten males to one female - that could end badly. In my experience, a slight excess of males is not a problem.

The quite wild spawning games of the goldfish are in great contradiction to their normal behavior and can certainly frighten you. It is often so lively that it seems that the Rogner are being pushed out of the water.(It is quite possible that Rogner who are too distressed will try to jump out of the water!)
This “hurry” during the spawning act is necessary because goldfish eggs die shortly after spawning if they are not fertilized.

Goldfish keepers sometimes report that newly introduced goldfish are hunted by the long-established ones. It is possible that the mucous membrane irritated when moving the net, which is now rougher and thus resembles the somewhat rougher skin of a roger ready to spawn. As a result, this fish, which actually has a weak injury, can attract milkers willing to mate, who then hunt it impetuously.

! It is very difficult to differentiate between the sexes of goldfish.
This is easiest during the spawning season, when the males develop their spawning rash on the gill covers and pectoral fins: small white raised dots. (Females develop very rarely, and then only weak spawning rash.) In addition, the males then often drive the females, who can then also be assigned and often (not necessarily) have a noticeably fat belly.

Outside the spawning season, it is very difficult to identify gender differences. The shape of the cloaca provides information, but you have to see the fish i. d. Take it in your hand: in females the opening is round and slightly raised (arched outwards; during the spawning season it is often clearly protruding, but very short laying tube), in males it is more oval to elongated and sometimes indented. In addition, the first ray of the anal fin is somewhat thickened in females.
A more statistical feature is the somewhat fuller body shape of female goldfish; Here the age, size and feeding status of the animals play too great a role within a cultivated form for this characteristic to be used to differentiate between the sexes. In some forms of veil-tail, the males are elongated when looking up, while the females, when viewed from above, have a slightly pear-shaped body; the rear part of the trunk is clearly thickened. In the veil cultivated forms, the pectoral and ventral fins of the males are significantly longer than those of the females. These characteristics are actually only useful when sorting young fish of the same type from the same rearing.
Chinese breeders also recognize the sexes by touching the skin: the scales of the males should be closer than those of the females. In addition, outside the spawning season, you can feel residues of it on the gill covers of older males who have already had a spawning rash.

In principle, gender recognition outside of the spawning season requires a trained eye; even professionals with years of experience can be wrong! The only way to be sure of this is to examine the anus opening with a magnifying glass.

! They are called fish eggs Spawn. A single spawn “korn” of the goldfish is approximately 0.5 to 1 mm in size. The spawn is deposited by the rogner (female) between fine-feathered plants or artificial spawning substrate and inseminated by the milker (male) - and usually then eaten in the aquarium ...
If you are actually able to save spawn, the fertilized eggs will hatch (they are crystal clear; whitish eggs are fungal) after 2 to 5 days, depending on the temperature. These then hang around for up to a week (on plants, panes, soil, stones) and consume their yolk sac. Only then do they swim to the surface and fill the swim bladder with air and eat the finest food.
Obtaining suitable feed and its frequent use are then the biggest problem.

! The newly hatched brood is often almost transparent and then briefly takes on the wild color. Subsequently, most of the fish with “metallic” scales turn dark black-brown (especially in the open air), but not the apparently “scaly” speckled calico shapes. This dark pigmentation in the upper layers of the skin is a camouflage color and characteristic of young goldfish. It recedes over time and the red gold color underneath becomes visible.
Often the summer fish available in stores still have black backs and fins or are slightly bronze colored all over their bodies. Both look very nice, but over time the black pigmentation recedes more and more.
The color change happens faster in warmer water. Goldfish that grow up in cold water after hatching stay black for much longer. Of course, there are also great individual differences. The color change phase can vary between six months and three years!
Also compare the question "Why is my goldfish becoming discolored?"

! It seldom happens in practice, but goldfish and koi can cross.
Carp fish are remarkable in this regard: it is not uncommon for members of different related species to spawn together, and several species and genus bastards are known (Leonhardt, 1904, Vogt & Hofer, 1909; both cited from Bohlen, 1996).
Populations of the gable Carassius gibelio consist exclusively of females on the western edge of its range that reproduce gynogenetically (cf. Biology I: Goldfish in the system); This happens because the female gables spawn together with other cyprinids and let their spawn be inseminated by the sperm of the males of closely related species. As a result, the embryonic development is stimulated without the cell nuclei merging (i.e. there are no crossings).
From the domestic common crucian Carassius carassius has been known since 1638 that they deal with carp Cyprinus carpio can cross (Leonhardt, 1904). When they spawn together, the cell nuclei fuse, and the resulting “carp” are unpopular due to their small size and (allegedly) poorly tasting meat. Plus, these bastards are sterile. Carp are therefore very reluctant to be seen by pond owners, and even in earlier times they were meticulous to ensure that valuable carp stock was not endangered by crucian carp. More information on carp carp can be found in Rudzinski & Skóra (1963) (quoted from Bohlen, 1996) and Skóra (1965).
Hybridizations are also between carp Cyprinus carpio and gold fishing / silver crucians Carassius auratus possible; scientifically described crossbreeds between ornamental carp (Kois) and goldfish z. B. von Taniguchi (1974), Taylor & Mahon (1977), Hume et al. (1983) and Pullan & Smith (1987). All of the works mentioned refer to animals that crossed in lakes, rivers and ornamental ponds without human intervention.

Carp as well as hybrids from carp / koi and silver crucian / goldfish have a pair of very short barbels (instead of two pairs of barbels - one of which is noticeably longer - for carp and no barbels for crucian carp). This is the most noticeable distinguishing feature for the layman.

Note: Instead of the previously used term in zoology (and also in human genealogy), des Bastards For crosses between two species (or for illegitimate children) many authors nowadays prefer the term des which originally came from botany and which sounds "genteel" Hybrids. “Hybridization” and “hybridization” are therefore often used synonymously today.

! The ears of the fish (not just the goldfish) sit inside the body: on the side next to the brain, behind the eyes. There are the same semicircular canals of the inner ear that we mammals have, but not yet a snail (cochlea). In fish, the saccule is very pronounced and takes on acoustic sensory functions.
Cyprinids (also goldfish) belong to the Ostariophysi (cf. Biology I: Classification in the system), a group of fish that has so-called Weber bones. These are small bones that connect the swim bladder to the inner ear. These bones fulfill the same task as our auditory bones in the middle ear: mechanical transmission and amplification of the sound pressure. In mammals this is absorbed by the eardrum (border between the outer and middle ear) and passed on to the ossicles, in fish by the swim bladder. Fish do not have an outer ear. The sound waves penetrate the tissue and cause the swim bladder to vibrate; In the ostariophysi, Weber's apparatus transmits sound pressure to the sacculus of the inner ear (which means it corresponds functionally to the middle ear). This enables goldfish to hear very well.
(Low-frequency) sound waves are also perceived with the lateral line organ. Historically, the inner ear even emerged from a part of the lateral line system that was shifted deeper.

This document was last revised on April 04, 2009
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