Head growths on goldfish

[SniperY]

A characteristic feature of two very popular groups of goldfish are what appears to be a raspberry-like growth on the head, which may look like a collection of warty growths.

To the biologist this is termed hypertrophy. Commonly called the hood, it is the result of the proliferation of skin tissue in the head region. Its development varies from the barely perceptible to the luxuriant when it may cover the eye.

The Japanese use the term Shishigashira (Lionhead) to cover the two kinds of fish. The Oranda Shishigashira (literally Dutch Lionhead) has a dorsal fin and moderately long fins. By contrast the Ranchu Shishishira has no dorsal fin with short fins. Both are twin-tails.

[SniperY]

Tracing its roots
Dr Yoshiichi Matsui, author of Goldfish Guide, originally suggested the hood was produced by a recessive mutation, but this idea was not developed in his later work - it is possible that developments in genetics after the period of his greatest activity in the 1930s made the conclusion less certain.

I do not think the hypothesis of a single recessive mutation is persuasive. Rudimentary hoods can be developed more or less spontaneously in varieties like the Veiltail and in hybrids produced between the Crucian carp and the former. This suggests the factor producing the hood operates on a simple presence-absence basis. In addition, there are other factors which appear to control where the development occurs. There are three regions of the head where the hood may develop: the cranial, opercular and infra-orbital.

Considerable controversy has arisen regarding the relationships between the Oranda and the Lionhead. Apart from the hood and the fact that they are both twin-tails, they are very different fish. The extent to which finnage length has developed is dissimilar, as are their body shapes.

The absence versus presence of the dorsal fin is the most striking difference. Dr Matsui does not consider them to be closely related in terms of their evolution. He does, however, accept that the long-finned Lionhead or Shukin could have arisen from a Lionhead and Oranda cross.

His view implies that the hood could have developed independently in response to selection. This is consistent with the observation of rudimentary hoods developing on mature Veiltails.

A notable development to be seen in Lionheads is the change in the form of the skull. This has become broader and massive, and is clearly seen when viewed from above. The contrast is most extreme when the Lionhead and Eggfish are compared - the snout of the Eggfish is sharply pointed whereas the Lionhead tends to have a very square jaw.

[SniperY]

As with the development of the hood, this is likely to have come about by the accumulation of several genes of individually small effect, probably as an indirect effect of successful selection for improved hood development. The greatest development of the square-jawed Lionhead is to be seen in some of the best Japanese Ranchu lines.

Who got there first?
Further controversy has developed as to whether Lionheads owe their origin to selection by the Chinese or Japanese. Following Dr Matsui’s line of argument, there is no reason why independent development could not have occurred in China and Japan.

The basic features of Japanese Ranchu were established over a century ago in Japan. Contemporary records of similar fish in China are lacking, yet outcomes of Chinese selective breeding show distinct differences from those of Japan.

The development of the Tigerhead has been mentioned, while that of the goosehead has recently changed to a form resembling a large, inflated beret rather than the typical goosehead of the 1980s.

Man Shek-hay, who wrote Goldfish in Hong Kong, calls the original form of Goosehead the High-head.

The Chinese have recently developed an enormous range of colours and colour patterns in hoods. Different areas of the hood may have different and often contrasting colours, as there may also be so for hood versus body colour. Some of these variants may be seen in current high-quality Chinese imports.

[SniperY]

Pompoms
Pompoms feature excessive growths around the nares (nostrils). The external nares can sometimes be enlarged as I have observed in goldfish and Crucian carp hybrids. It is possible that pompoms might have developed by a process similar to that which produced hoods.

Pompoms are valued when they have paired, compact spherical structures. If these are without definite form and loose, they are unsightly and could be drawn into the mouth during respiration.
Initially, Pompoms in this country were dorsal-less and with a body conformation similar to that of the Bubble-eye.



Nowadays they have a dorsal fin, thus producing a situation comparable to the Ranchu/Oranda.

The other features of the dorsal-less and dorsal finned variants show a similar set of differences as between their hooded counterparts.

Pompoms have been introduced to other varieties as additional features: most Celestials offered for sale these days have them, although Nationwide Standards consider such fish to be not eligible for showing.

Pompoms can present a problem in some varieties - like those with hoods. Intrinsically these characteristics are incompatible aesthetically, and even more so when features like telescope eyes are combined.

Genetic control of the pompom character has not been studied (or the results of such studies are not available), but it is a feature which can be transferred between varieties.

For the breeder, the prime considerations should be shape: a compact form and as large a size as is compatible with overall appearance.

[SniperY]

Pearlscales
The Pearlscale, according to the Nationwide Standard, is a fish with a general body conformation close to the Fantail.

This shows a special and peculiar feature of an almost spherical body form. The special characteristic is the scale, which has a central boss with a heavy guanine deposit that is the "pearl".

In a good example, the pearls are large, even in development, and occur in continuous rows.

The scales may be opaque or transparent, with the result that both the usual metallic and calico colour patterns may develop.

Genetic control seems to be simple - it is probably produced by a simple recessive mutation. It is another character that is readily transferred by cross-breeding, and pearlscale forms of any variety could be produced if desired.

The Pearlscale can also interact with the Oranda to produce (instead of a hood) a double inflated sac-like fluid-filled structure on top of the head.

[joelwong]

This one must go home, make a cup of coffee, print out, slowly read

[Megabetta]

This one must go home, make a cup of coffee, print out, slowly read

I reckon mich would want to read this detailed information about goldfish. Ask her to register as a member lah.

[SniperY]

I reckon mich would want to read this detailed information about goldfish. Ask her to register as a member lah.Bro, get more gf fanatics here to talk about gf
:big_smile: :big_smile: :big_smile: