Black colour in goldfish - from Black Moors to Black Ranchus and Black Orandas

The Black colour in goldfish

When one thinks of a black goldfish, Black Moors is usually the first type that comes to one's mind.

The Black Moors (Kuro Demekin), a black metallic scaled telescope eye goldfish, was first developed in China about 200 years ago (called Dragon eyes). Shipments bound for export stopped in Japan en route and some were sold to locals there and the breed was maintained by the Japanese until it was re-introduced to the rest of the world.

The Black Moor goldfish, when they are first born, are originally normal wild bronze or silver grey colour. Generally, around 30 days to within 3 months after birth, the yellow and black pigments (melanophores) begin to intensify. As a result, the black colour of the Black Moor goldfish appears. This generally coincides with the development in the protusion of the eyes.

It was once held that the black colour in goldfish has something to do with the telescope eye (see Matsui's The Goldfish Guide), as no other goldfish breed at the time back until the 1970s had self-coloured black all over the body (until the appearance of black ranchus and orandas and black bubble eyes).

In good Black Moor specimens, no depigmentation of the black happens. However, in poor specimens, depigmentation occurs 2 - 3 years later, resulting in a yellow, orange or red telescope eye goldfish, ie Aka Demekin.

Scientific studies
Kajishima (1977)* studied the colouration of Black Moors and stated that it ususally did not depigment its melanophores during its life. Instead it produces more of them during development. He noted the four depigment genes as 2 multiple gene pairs, ie, dp1dp1 and dp2dp2. He also noted that the Black Moors had the dp1dp1dp2dp2 genes in their recessive state.

On that basis, Kajishima found that when a Black Moor mated with a dominant depigmented wakin, Dp1Dp1Dp2Dp2 (eg, orange colour), the resulting progency will be 100% depigmented like the wakin.

However, when a goldfish depigments, it always goes through a phase of black before the gold appears, ie, intensification of the number of yellow and black melanophores.

This change from bronze silver grey to black, followed by the destruction of the black melanophores, leaving the yellow and red melanophores, resulting in a yellow or red or orange fish, depends on whether the fish has yellow or red (or both) melanophores.

Therefore, depigmentation in a goldfish goes through three colour phases:
1. Wild silver grey, bronze colour phase (yellow and black pigment cells)
2. Black colour phase (intensification of yellow and black pigment cells)
3. Orange, yellow or red phase (destruction of the black pigment cells, leaving the red yellow pigment cells in isolation (red or yellow) or in combination (orange))

On that basis, Kajishima would naturally get all his frys from the Wakin and Black Moors cross to depigment and it would be incorrect to state that Black Moors have dp1dp1dp2dp2 genes in their recessive state. This is because Black Moors are already on the first stage of the depigmentation process, ie, turning from bronze olive grey to intense black. Therefore, Black Moors should have some of their depigment genes in the dominant state, but as a strain, the Black Moors depigmentation process is halted or switched off when the fish is all black, and the decolouring does not proceed to the next stage, ie, destruction of the black pigments to the yellow orange phase.

Kajishima should have used wild bronze olive grey goldfish instead and to label them as dp1dp1dp2dp2 and to cross them with the wakin for determining his research results.

Accordingly, it is more "correct" to state instead that Black Moors do depigment, but they have incomplete depigmentation, ie, the onset of intensification of the yellow and black pigment cells did not follow through with the destruction of the black melanophores (pigment cells). That means the depigmentation process got "halted" when the fish turned to black, and did not follow through with the destruction of the black pigment cells.

As to when the fish starts the depigmentation process to when it halts the depigmentation process, ie, suspending the destruction of the black pigment cells, leaving the goldfish permanently black throughout its life, is a genetic process that has been pretty much fixed in the Black Moors, but not in the Black ranchus or orandas, as they have more a recent heritage, ie, last two decades as opposed to last 200 years.

Black in non-telescope eye goldfish
Black ranchu lionheads, black orandas and black bubble eyse have all appeared (but not black comets or common singletail black metallic scaled goldfish). It was once suspected that perhaps the black ranchus and orandas were really black telecope eyes hiding behind their head growths. However, this does not appear to be the case, when black bubble eyes and to a lesser extent, grayish black pearl scale goldfish appeared in the market. They do not have telescope eyes.

Difficutly in breeding black frys from these non-Black Moor goldfish
Many breeders had no difficulty getting their black ranchus or orandas to breed, but they ended up with bronze silver grey babies that do not darken to black as they grow.

I don't know how long these breeders kept their bronze juveniles for, as goldfish with their depigment genes in their recessive state might take a long time to depigment, ie, they do not depigment until in their second or third year or more. Given many breeders noted on forum threads that their black ranchu babies did not decolour but remained bronze, it is suspected:
1. these ranchu babies inherited the recessive genes from both black ranchu parents, therefore, they do not darken to black like their parents. Goldfish have a tendency to revert to their wild bronze olive grey colour in successive generations. It is the efforts of human beings in constantly select and breed the yellow orange colours to stop the reversion of goldfish back to their wild state.
2. it also means that black ranchus when bred together, have a tendency to complement each other and provide a complete set of recessive genes to their frys in the homozygous condition (recessive state), ie switching off the depigmentation process altogether, ie, the number of non-depigmentation genes are increased when compared to their parents, so the frys are represented by dp1dp1dp2dp2, therefore they won't start depigmentation process at all. That is, they won't turn black but to remain bronze.
3. It also means the black ranchu parents have at best Dp1dp1Dp2dp2, ie, not having both pairs of dominant depigment genes Dp1Dp1Dp2Dp2 (ie dominant in the homozygous state). Because if they did, the parents themsleves would have turned orange first after their black phase, and their frys would inherit Dp1Dp1Dp2Dp2,ie, four dominant depigment genes in their homozygous state and depigment and also turn orange very early on. Instead, by having Dp1dp1Dp2dp2 genes in their dominant heterozygous state, these ranchu parents switch on the depigmentation process, ie, the black instensification phase of the depigmentation process, but then the black melaophores destruction phase is then halted, leaving a black goldfish.

How to switch on the 'depigmentation' button?
On that basis, in order to 'switch on' the depigmentation process, it is necessary to breed black ranchus with:
1. non-black ranchus, those that do depigment (eg, orange ranchus) but these orange ranchus are those which not only took a long time to depigment, ie, in their 2nd or 3 rd year before they change colour (eg, Dp1dp1Dp2dp2 or Dp1dp1dp2dp2, having one or 2 dominant depigment genes out of 4, so took a long time to depigment), and when they do eventually depigment,
2. they took a long time to lose their black colour to become orange, and preferably ones that still have a lot of dark black pigments (patches of dark black on their body and fins for quite some time as adults, ie, never loses their black completely).

What this cross will do is to 'trigger' the onset of depigementation, ie, the intensification of the black colour in the frys, but then hopefully, to switch off the depigmentation once the fish is black, so the orange phase does not then follow the black phase.

How to trigger the onset of black pigmentation and then to keep it?
Goldfish farmers have long noted that frys from the same parents, those born in warm summer months have a high percentage of depigmentation, but those born near early to mid-Autumn have a low percentage of depigmentation. Therefore, the environment has a lot to do with triggering depigmentation, apart from genetics.

The key to switch on depigmentation, ie turn bronze silver grey to intensification of black colour needs:
1. Warmth, ie, warm water
2. Light
3. light bottom susbtrate

Once the fish is starting to darken to black (ie, onset of black instensification begins), the reverse is required to halt further depigmentation of the destruction of the black pigments. This needs:
1. cold water
2. shade, dark green water environment
3. dark soil substrate bottom

As said, Black Moors has been bred for its black colour for 200 years, they have a high chance to depigment from 30 days to 3 months, ie, they have been selected repeatedly or been 'programmed' to darken and then to halt the depigment process once they are all black. Any which do not blacken or after they became black, then continued to turn orange afterwards are discarded.

On the other hand, black ranchus and black orandas only have been around for 20 years, they are not fixed as yet, and will require a far longer period to be programmed (fixed) to the desired outcome.

Here's a real challenge for the keen amateur breeder who meddles in both genetics and the environment. You want the goldfish to start the depigmentation process, and that has been determined scientifically, ie, by the number of depigment genes, yet the depigmentation process is then halted once the fish turns all black. This second part has not been scientifically resolved.

Note) With black Orandas, a way to help to get them black is to cross them with Black Moors. After all, both have dorsal fins, and the frys will all be normal eyes in the F1 generation. Then select the frys which still have good head growths from the outcross. Smaller head growth in exchange for fixing the black colour.Then cross it back to the black Orandas to get the head growth back.

*Takao Kajishima, Genetic and Developmental Analysis of some new color mutants in the Goldfish, Carassius auratus, Genetics 86:161-174 May, 1977

© Bill L 7 June 2009

Blood is thicker than water: for a goldfish

Goldfish have feelings

This time, I deviate from the usual genetic theme of my goldfish blogs.

Instead, my focus in this post is to document a goldfish experience that I could never forget.

Back in the early 1990s (around 1991-1992), one of my linear scale comet goldfish jumped out of my fish tank and landed on the lounge room floor. It was not discovered for quite some time.

By the time it was found, it was quite 'dried'. The eye which was against the floor kind of stuck to the floor, and although I was able to remove it, the cornea was damaged and my Linear goldfish survived the ordeal afterwards with a blinded eye.

The thing that left a lasting impact on me from this was when I returned this Linear scaled goldfish back into the tank was one of its tank-mate, a part-red and white comet swam close by it and kept circling it. The Linear was pretty exhausted from the near death ordeal, and was lying flat on one side grasping. The part-red and white comet swam around the Linear scale goldfish, and on many occasions, tried to use its head to help the Linear scale goldfish to balance 'upright'. It repeatedly used its head to nudge the Linear scale and did that for quite some time to try helping the other fish to balance upright.

None of the other goldfish in the same tank did anything at all, they all ignored the Linear scale goldfish.

The Linear scale goldfish eventually recovered its strength and was able to balance itself upright, then the part-red and white comet swam away. My linear scale goldfish survived the 'out of tank' experience and lived for about a year longer.

When it got sick again later and died in the tank, the part-red and white goldfish did not pay any attention to the Linear scale goldfish, as it once did.

However, what the part-red and white comet did on that particular day when the Linear scaled goldfish jumped out of the tank was purposeful and was deliberate. To me, it's only purpose was trying to help the Linear scale goldfish.

It was something that I witnessed and which I could never forget. I can only think that goldfish have feelings too and at least in that instance, I saw one goldfish trying to help another when it was sick.

Blood is therefore thicker than water for a goldfish too...

© Bill L 6 June 2009