Metallics and Masks

Victoria Parnell

This month I’d like to address two of the recent color types that generate the most questions via email from this website: the metallic and the masked betta. I would like to say by way of disclaimer that, as of this writing, nobody really can claim to have solved all of the mysteries of these traits since they require more intensive study and experiment that most of us have the time to dedicate to a hobby. However, the betta hobby has it’s advantages, the first being it’s enthusiastic hobbyist breeders, many of whom are fascinated by the metallics and the masked bettas and are breeding them like crazy and recording the results. The second major advantage our hobby has is named Dr. Leo Buss.

Leo Buss is a PhD and the Professor of the Department of Geology and Geophysics at Yale University in Connecticut. He is also the author of the Bettas…and More column found in FAMA Magazine, and has given several discourses in betta genetics for the IBC. 

Because Dr. Buss is also interested in the metallic betta he’s been able to break it down somewhat by use of an electron microscope to ‘see’ beneath the metallic layer to the color layer it is covering up. Based on his findings and the experimental breedings from several hobbyist breeders, we can draw a clearer picture of the metallics and masked bettas, which is the first step in the direction to completely understanding what they are and how they effect other colors.

Copper/gold HM male – Suporn Khumhom (Bluebetta)

When I questioned Buss about his experiments, he confirmed that the metallic and masked traits came from hybrid crosses of B. splendens to other wild bettas such as B. imbellis: ‘I looked at several Betta imbellis from different lines under the microscope to determine the ‘wild-type’ state,’ says Buss. ‘All displayed yellow reflecting iridiophores in the distribution noted in the FAMA article.’

Blue mask HM male – Breeder unknown

Blue mask HM male - Breeder unknown

The article in reference was the November 2005 ‘Bettas…and More’ column, in which Buss suggested that there is a gene which inhibits the spread of metallic color, which he called the ‘no metallic spread’ or ‘NMS’. His breeding experiments seemed to indicate that gene being a simple Mendelian recessive. Buss also used a ‘+’ notation (implying a ‘wild’ trait) for metallic colors such as copper, and noted that it was recessive to the Bl (blue) gene. Without the + gene the copper betta was a simple steel blue, the blue/green (‘teal’) betta a royal blue, and the dark metallic green was turquoise. 

Of interesting note is that, in an email in August, 2005 Buss noted that, although both the metallic and masked genes came from the hybrid crosses, they were not the same, and each could exist independently of the other. This is what makes fully-masked solid color pure iridescent blues not only possible, but within reach in a few generations. Buss states the metallic influence can be bred out by the F4, although it must be said that in my own experience, once the masked gene is introduced it is almost impossible to be completely rid of it. Even after several generations of outcrossing to pure iridescent (non-metallic) fish, I was still seeing the parti-masks and blue lips characteristic of the hybridization. 

Breeding Copper
Because solid copper/golds are genetic steel blues, breeding copper x copper will always yield 100% copper fish. The only exceptions occur in those spawns which have another recessive gene, such as marble. Here are some other results: 

Copper/gold x Turquoise green: All green, variable metallic expression.
Copper/gold x Royal blue: Blue/green and ‘grass’ green, all with variable metallic expression.

Here was the really interesting one:

Copper/gold x Melano: All green with variable metallic expression. Some fish were more turquoise-colored than others, but all were within the spectrum of green. Copper/gold being + over steel blue with no melano geno, what you would expect to see from this spawn is 100% steel blues. However, because a fish that is heterozygous for the metallic trait still displays the metallic phenotype, the yellow reflecting iridiophores present made these fish look ‘green’.

The variation of the metallic expression exists not only because the number and spread of the yellow iridophores varies from fish to fish, but because the crystals contained within the iridophores themselves also vary in size.

In my ‘Brass’ line, I initially bred a copper/gold to a yellow just to see how the + gene would affect red and non-red. This is what I got:

Copper/gold x Yellow: gold scale reds, cambos, green/red multis (like Imbellis)
F2 (green/red multis): Gold scale reds, cambos, yellows, green/red multis
F3: ‘Brass’ (gold body, red fins).

In addition, I have since bred copper/gold to opaque (and gotten ‘Platinum’), to red (metallic red), to cambodian (metallic cambo), to black lace (black/green and black/copper), to MG (metallic MG), and to marble. In all of those matings it can accurately deduced that the + gene does not work as a recessive that requires two carriers for + in order to appear, but that the + gene effects other colors in subtle ways from the very first filial generation. 

Others I’ve seen but haven’t worked with extensively are metallic yellow and metallic orange.

The Masked Trait
In normal iridescent fish that do not carry the + gene, the body and fins of the fish are blue, green, or steel and the heads are typically dark brown or black. Breeding to metallic usually also introduces the masked gene, which causes the spread of color into the face and head area of the iridescent betta, producing a true solidly-colored fish. The masked effect can work independently from the metallic gene, and can be reduced in expression (so you can have a copper/gold with a dark solid head) or increased so that it completely covers the head and body of the fish in what looks like body armor. It is possible to breed to metallic to get the masked trait, and then selectively breed away from the metallic gene while keeping the mask, thus producing a solid iridescent fish. 

The Pluses of the + Gene
The typical metallic/copper iridescence is caused by various-sized iridophores in the crystalline layer. In pure iridescent blues, greens, and steels the iridophores are all the same size and shape, which causes the ‘normal’ iridescent appearance. The various sizes of the iridophores in metallic bettas influences the refraction of the light spectrum which is one theory to explain the color changes which are observed in metallics. 

The effect of the metallic gene on other colors is that it can produce a ‘whiter’ white opaque and a ‘redder’ extended red by thickening the color and ensuring it’s spread over the head and face. It can also produce a ‘blacker’ black melano by covering the iridescent color normally faulted in blacks by the reflecting yellow iridiophores. An extremely iridescent black would look copper-bodied with black fins instead of steel-bodied, and a good melano with only minimal iridescence appears to be very solidly black. An interesting phenomenon I’ve noticed in my metallic black line (‘super blacks’) is that the reflective yellow scales sometimes seem to ‘flake’ off, leaving a dark, flat black color underneath. 

The metallic gene has also produced some of the most beautiful bettas ever seen today in a variety of colors that play in the light and dazzle the eye. The only thing that is cause for concern is that the ‘old’ color lines will be lost entirely if they aren’t intentionally preserved, since the + gene effects everything it touches so profoundly. It is important, therefore, to keep pure lines of iridescents, reds, yellows, opaques, melanos, and more that are completely free of the + gene.

Done responsibly, the + gene is both fun and fascinating to work with. How many different colors is it going to help create? That question is still to be answered. But we’ll all have a lot of fun finding out!


Reprinted with permission from Bettas4All

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