RAIN GARDEN ORNAMENTALS

 

UNDERSTANDING GOLDFISH COLOR

-steve hopkins

May, 2010

 

To a large extent, bright colors and color variation is the essence of goldfish.  Were it not for the colors, goldfish would not have been developed to any significant degree and they would not be the popular ornamentals that they are.  When evaluating a goldfish, body conformation and fin placement are the most important criteria.  Without good body conformation and fins the fish is junk and consideration of color and pattern should be the last thing we look at.  “Should be”, but let’s face it, color and pattern drives most goldfish purchases. 

There are similarities and some important differences between goldfish and koi color development and maintenance.  To discuss goldfish color, we must discuss goldfish scale types.  There are three basic scale types: metallic, nacreous and matt.  The scale type strongly influences the color possibilities and the color stability.   

Metallic Scale

The underside of a metallic scale has a solid coating of guanine, a crystaline pigment which refracts light.  Guanine is considered a pigment and cells containing guanine are called iridophores.  Guanine makes the scales opaque and give them a shiny metallic appearance.  Guanine may also be present in parts of the body which are not scaled like the gill covers.  When there are red or black pigment cells overlying the guanine, our eye sees shinny red or shiny black.  When there are no other pigment cells overlying the guanine, our eye sees a shinny white or silver color.  Guanine is also found in the outer layers of the skin. 

Metallic-scale goldfish can be orange/red, white, yellow, black, metallic blue, brown, bronze or a variegated combination.   Solid colored metallic-scale goldfish are often called “self colored”.  There can also be a variegated pattern with two or more of these colors.  Sometimes you hear the variegated pattern called “piebald” or “motley”.

Self-colored orange/red is the most common metallic-scale goldfish color.  Because it is so ordinary, self-colored orange/red is less highly valued.  The orange/red is produced by red pigment cells, called erythrophores, and yellow pigment cells, called xanthophores, in the scales and skin.  The erythrophores and xanthophores typically occur together.  The density of the pigment cells and the relative number of the two types produces various shades of yellow, orange and red.  While uncommon, some metallic-scale goldfish have many erythrophores but few xanthophores.  Such a goldfish will have a pleasing deep red color.  Even more uncommon is to have xanthophores but no erythrophores giving the fish a lemon yellow color.  Self-colored goldfish are usually very stable.  Diet and environment may influence the color saturation, but seldom changes the hue. 

The second most common color in metallic-scale goldfish is a variegated pattern of red and white.  Virtually every goldfish variety is available in variegated red and white.  The more white there is in a variegated pattern, the more intense the red.  In almost all cases, xanthophores are present, but the erythrophores are produced at such a high density that the red seems to over-power the yellow.  Variegated red and white patterns are fairly stable.  Sometimes the red pathces will expand or contract a little, but not by much. 

Color patterns in metallic-scale variegated goldfish are very weakly heritable at best.  For the most part, the variegated pattern is formed during the early stages of fry development and is not something they are born with.  A goldfish can inherit the potential to form a variegated pattern, but does not inherit the pattern itself.  When two red and white variegated metallic-scale goldfish are mated, most of the offspring will be self-colored orange/red, some will be red and white variegated, and a few will be solid white.

Black is produced by melanin pigment in melanophores.  Before discussing black, we need to mention the process of demelanization.  All metallic-scale goldfish develop a greenish bronze color during the first weeks of life.  This is often called the “wild” color because it is similar to the color of wild Gibel carp.  The wild color is produced by a combination of red, yellow and black pigments.  Later, at the age of about three months, many metallic-scale goldfish undergo the process of demelanization.  During demelanization, first the amount of black pigment intensifies and the overall appearance becomes very dark.  Then, the melanin is destroyed leaving only the red and yellow pigment cells behind.  The end result is an orange/red or red and white variegated color.  Demelanization is a heritable characteristic.

Black goldfish have undergone the first step in the demelanization process.  The amount of black pigment has increased.  However, black goldfish failed to undergo the second part of the demelanization process and the black pigments were not subsequently destroyed.  The first black goldfish variety was the black moor.  The gene for the black coloration is strongly linked to the gene for telescope eyes and it continues to be difficult to get one without the other.  But, all black moors are not created equal.  Most have some lighter-colored scales on the belly.  The ones with the lightest color on the belly are susceptible to completing the demelanization process later in life.  At the age of one to three years they may start to slowly lose the black and turn orange/red.  Some only loose the black on a portion of the body and tri-color telescopes.  These are very attractive and generally more desirable than black moors, but there is no guarantee that the rest of the black will not be lost at some point in the future.

Because the gene for maintaining metallic black and the gene for telescope eyes is linked, black in other varieties is even more susceptible to being lost later in life.  Black ranchu may have a nice black color, but it is difficult to maintain.  One secret to maintaining the metallic black color is to expose them to plenty of natural sunlight.   In the market today, there are two strains of black ranchu.  The Chinese strain have better bodies and a strong caudal peduncle, but the black is not as intense.  The Thailand strain of black ranchu have a deep laquer black color, but the bodies are thin and not strong or imposing. 

There are also black lionhead, black oranda, black crown pearlscale, and black bubble-eyes.  The quality and intensity of the black on black oranda is generally not as good as in the other varieties, however the black seems to be more stable in oranda and less likely to be lost later in life.  In recent years, a black comet has also appeared on the market.  The origins of this variety are obscure, but the body shape and the remnants of barbels under the chin indicate that black comets are actually a hybrid between a goldfish and another species of carp; probably a koi or common carp (Cyprinus carpio).  They are probably sterile and cannot reproduce.

There are also pandas and tri-color metallic-scale goldfish.  Black and white pandas are very attractive and popular goldfish but, here again, the black has a propensity to disappear later in life.  On one sense, pandas are the transitional phase of a solid black goldfish which is in the process of turning white.  Sometimes an individual will be stuck in this transitional phase for many years, but other times it is only months.  A tri-color goldfish is like a panda but with red, black and white.  The red is fairly stable, but the black could disappear and leave a red-and-white variegated goldfish behind. 

The most important thing to remember here is that black can be unstable in metallic-scale goldfish.  This is one of the two great conundrums in goldfish keeping.  Black metallic-scale goldfish are attractive and well-defined patches of black in combination with red and/or white can make for the most striking goldfish of all.  Unfortunately, there is no way to predict when or if the black will disappear.  The black is most prone to fading away when the fish is moved to new quarters or undergoes another major disruption.  So, to add insult to injury, the black is most prone to fading after it has been shipped from the farm and entered the distribution chain.

Finally, the black pigment, melanin, is usually found in specialized pigment cells called melanophores.  The melanin can be concentrated in a small spot in the center of the cell, or it can spread throughout the cell.  When the melanin is spread throughout the cell, the cell appears darker.  The fish has some control over whether the melanin is concentrated in the center or spread throughout the cell.  So, at times the overall appearance can be very dark while at other times the black can seem to fade to a grayish color.  To some degree, this happens every day with the fish being slightly darker during the day than it is at night.  The lighting, background, fish health, and other factors can thus influence the intensity of the black coloration.

While most of the black pigment is associated with melanophores, melanin can also exist free in many types of tissue.  If there has been mechanical damage, ammonia burn or other insult to the skin or scales, we see it turn black during the healing process.  This phenomenon is called “melanophore migration” but that is a misnomer because it is not melanophore cells which migrate to the injury, but free melanin.  Free melanin may also develop over parts of the body in response to the use of certain medications.

Metallic blue goldfish look more grey than blue to most people.  Bluish grey may be a better description.  This is not to be confused with the jay blue or sky blue found in calico nacreous-scale goldfish.  There are several shades of metallic blue and many metallic blue individuals also have brown patches here and there on the body.

The metallic blue is created by scattered melanophores.  The melanophores and black pigment are identical to those found on solid black goldfish, but the melanophores are spread out rather than being densely packed together.  This “dusting” of black pigment in the absence of any red or yellow pigment gives the fish a bluish grey appearance.  If there are patches of red and yellow pigment, these appear brown when combined with the dusting of black.

As mentioned above, black can be unstable in metallic-scale goldfish and this includes the dusting of black which creates metallic blue.  If the black fades away a metallic blue goldfish becomes a white goldfish.  If the metallic blue individual has some brown patches before the black faded away, the metallic blue fish becomes white with red patches.  Even though the black is unstable, the red and yellow pigments do not usually disappear.

Metallic chocolate, bronze, purple and green (the color of wild carp) each contain all three color pigments (black red and yellow) but in different proportions.  If the number and density of melanophores were increased on a geen/wild goldfish, it would appear chocolate brown.  If the amount of yellow pigment were reduced the resulting color is called purple.  Whoever decided to call them “purple” and “green” had an over-active imagination or suffered from wishful thinking.  They are not really purple or green, just a brownish grey with a purple or green tint.

Calico or Nacreous Scale

Calico’ and ‘nacreous’ are often used interchangeably when discussing goldfish color.  Color development in nacreous-scale goldfish and metallic-scale goldfish is very different.  Both have the same three pigment colors (black, red and yellow) but changes in the amount of guanine and placement of the pigments influence how the colors are expressed.

Nacreous-scale goldfish actually have three types of scales.  Some scales have a solid layer of guanine on the underside and color pigments in the upper layers which make them look like normal metallic scales.  Other scales are transparent with a matt finish, but scattered guanine is present in the outer layers of the shin which gives a pearlescent shine to the clear scales.

Nacreous-scale goldfish can have color pigment in the outer layer of the scale and can also have pigment in the skin.  The skin pigments can be on the surface of the skin just below the scales, or embedded deeper in the shin.  Pigments both in the scales and below the scale in the skin has a remarkable effect on the color our eye perceives.  Black pigment in the scale appears black to our eye.  Black pigment in the upper layers of skin appears grayish.  Black pigment deeper in the skin appears blue to our eye.  Blue in a nacreous-scale goldfish really is blue, like a blue jay.  Red and yellow pigments can appear red, yellow and orange or, in combination with black, can create purple, brown, and other hues.

Black in nacreous-scale goldfish is stable.  If anything, black tends to deepen and expand over time in nacreous-scale goldfish.  But, while nacreous-scale goldfish have more color variations and stable black, they may not necessarily be more attractive.  Often, the colors are not as bright because they lay under the scales.  Compared to metallic-scale, the colors have less shine because of the reduced amount of guanine.  The sharpness of the separation between colors may not be very good in nacreous-scale goldfish as the colors tend to blend from one into another.  Instead of having large distinct patches of color, nacreous-scale goldfish tend to be more speckled; especially the black. 

In recent decades a special sort of calico called 'kirin' has been developed.  Kirin offspring and traditional calico calico offspring tend to segregate differently.  As noted above, when two traditional calico goldfish are crossed, 50% of the offspring are calico, 25% are metallic and 25% are matt.  When two kirin are crossed there are fewer true metallic.  About 25% look metallic at first glance but many, if not most, have a few clear scales.  Likewise, about 25% appear matt at first glance but most have a few scattered metallic scales.  Kirin goldfish often have significantly more black than traditional calico.  The black can can be diffuse across most of the fish and it can occur in dense, distinct patches.  Kirin goldfish also tend to have more metallic scales interspersed with the clear scales.  But, the kirin characteristic does not breed true and many or most of the offspring will look more like traditional calico.

Neither metallic nor nacreous goldfish are better, they are just different.

Matt Scale

The color in matt-scale goldfish is poor or non-existent.  Matt scales have no reflective guanine.  Thus, the scale is transparent although some of this transparency is lost as the fish ages because of scale thickening and ossification.  Goldfish with matt scales generally do not have any of the red, yellow or black color pigments either.  Young goldfish with matt scales are pinkish and are commonly called “pinkies”.  The pinkish color is not from surface pigments, but rather is the caused by blood in the skin and muscle tissue showing through the transparent scales.  Most mature matt-scale goldfish are a dirty white with, perhaps, a few grayish areas.  Matt goldfish are culled by the breeder and seldom enter the marketing chain.

Colored matts exist, but they are very rare and the color is dull due to the absence of guanine.  Whether a goldfish is a colored matt or a nacreous goldfish which was born without any guanine can only be determined but progeny testing.  The genetic make-up is unraveled by comparing the percentage of metallic, nacreous and matt offspring.  Scale type is a heritable characteristic.  Two metallic-scale parents will produce 100% metallic-scale offspring.  Two parents with the mutant gene for matt scales will produce 100% matt offspring.  Metallic and matt are homozygous conditions; that is, the fish has two doses of either the metallic or matt gene.  Nacreous is a heterozygous condition as they have one dose of the metallic-scale gene and one dose of the matt-scale gene.  So, when two nacreous fish are mated, 50% of the offspring will be nacreous, 25% are metallic and 25% are matt.  A metallic crossed to a nacreous produces 50% metallic and 50% nacreous offspring.

Color Enhancement

The color intensity of an individual goldfish is influenced by the environment and diet.  Goldfish are kept in everything from indoor aquaria to outdoor ponds.  The colors will be less intense in dim lighting, partially because of pigment constriction in chromatophores as discussed above.  Artificial lighting will partially overcome this problem.  But, high lighting grows algae and dramatically increases aquarium maintenance.  Furthermore, even when you try to mimic the black-body spectrum of sunlight (about 6,000 Kelvin), artificial lighting does not usually produce the color intensity achieved in an outdoor pond.  This may be due to other differences in natural and artificial lighting such as the absence of ultraviolet radiation, or it may be related to diet. 

A lightly-stocked outdoor pond will have natural forage with color-enhancing properties.  In outdoor ponds, red is more vibrant and less orange while black becomes darker and deeper.  However, white usually suffers in an outdoor pond and may take on a yellowish tinge.  This seems to be a result of consumption of algae, duckweed or other plant life which contains large amounts of xanthophill, a yellow pigment.  The fact that red color is intensified and appears less orange, even when the fish is ingesting fairly large amounts of xanthophill, is a paradox because the red erythrophores occur in combination with yellow xanthophores.  Evidently, the erythrophores are able to over-power the xanthophores  making the color appear more red to our eye.

Commercial goldfish feeds are designed for use in indoor aquaria and often have high levels of color enhancers like astaxanthin and other carotenoids from crustaceans and Spirulina.  There are several problems associated with exclusive use of commercial goldfish pellets and one of them is excessive color enhancers in some brands.  Astaxanthin enhances red pigments.  This works fine for self-colored red goldfish.  However, most goldfish also have some white variegation.  Excess astaxanthin will cause the white to become pinkish and the red will smear into the white areas.  Yellow and black pigments will be largely unaffected by the color enhancers used in commercial feeds.

The effect of water hardness on color development seems to be less pronounced in goldfish than it is in koi.  Very hard water will intensify black to some extent.  But, soft water does not seem important in maintaining red and white.  Trying to manipulate hardness often results in instability so it may be best to accept your ambient hardness as long as there is sufficient alkalinity to prevent a pH crash.

So, everything we do to improve color will help in some respects, but have adverse side effects as well.  What’s a goldfish keeper to do?  Perhaps the best approach is to take the middle road and use everything in moderation.  Provide lighting, but not too much.  Strive to provide water quality and a diet which focuses on fish health and let color take care of itself. 

Variety Colors

Most goldfish varieties can be any color  including red, white, variegated, calico, black, blue, chocolate, green, etc.  However, some varieties can legitimately have only certain colors. 

Shubunkin are always calico.  Most show standards require that a shubunkin have a combination of blue, red and black but if the goldfish is calico with a single tail then it is a shubunkin.  Common goldfish (hibuna) and comets must be metallic red, white or variegated.  If a goldfish has the body shape of a common goldfish but is calico color, then it is called a London shubunkin.  If a goldfish has the body shape and long single tail of a comet but is calico color then it is called a Japanese/American shubunkin.

Jikin, are always metallic red, white or variegated although it is really the shape of the tail which defines this variety.  The best jikin are white with red fins, lips and gill cover; a color pattern called “twelve points of red”.  Nankin are always metallic red, white or variegated and white with the twelve points of red is most desirable in this variety as well.  Tosakin are metallic red, white, variegated or green but, again, it is the shape of the body and tail which defines the variety.  Japanese ranchu (top-view ranchu) must be metallic red, white or variegated.

Finally, certain color patterns are named, regardless of the variety in which they occur.  Metallic red and black is called “apache”.  But, if the black occurs in vertical stripes it is called a “tiger”.  We mentioned the metallic twelve points of red in jikin and nankin but this patter can show up in most other varieties, especially wakin and hibuna.  Metallic white goldfish with a red patch on the head are being called “tancho”; a term borrowed from the koi community.  Likewise, red lips on a white head is called “kuchibeni”.  A metallic white oranda or lionhead with a red head-growth is called a “red cap”, but a metallic white ranchu with a red head-growth is usually called a “red-and-white ranchu”.  Go figure.

Denouement

 When selecting a goldfish, focus first and foremost on the body conformation and fin placement.  A good body will remain a good body as long as the goldfish is properly cared for.  Fins lengthen and usually improve with age if the fin placement is correct from birth.  Color, on the other hand, can be more risky.  The color may become more attractive over time, or it may deteriorate.  By understanding the influence of scale type on color, the inherent stability (or instability) of various colors, and the impact of diet and environment on color, there will be fewer surprises ahead.

 

 

 

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