A koi betta is simply a commercial label (strain name/nickname) for a specific coloration of a marble betta; usually a cellophane based body with red and black spots of color. Like a koi fish!
So, what's a marble betta?
Marble is a name for a transposon (jumping gene): a DNA sequence that can change its position within the genome. As a result, marble bettas often have splotches of pigment (or areas without pigment) all over their body and fins. Because the marble gene is a transposon, its color is unstable, and often marble bettas will develop more or less color throughout their entire lives; a result of the gene "switching" pigment on or off. A transposon cannot transform into a normal gene, so there are no marbles that are guaranteed to hold their color pattern throughout their lives. It can affect all pigments on the fish, making for a literal rainbow of possibilities.
A koi betta is a marble betta! However, not all marble bettas are koi. There are many commercial labels for popular color mixes of marble bettas, pictured below. (Click picture for original source.) |
IridescentBlackRedCellophane |
Marble is not a color, rather it's a gene that affects the color layer it resides in.
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