Gold marble question....

Do 'gold marbles' have to have black on them? I ask this because I have a batch of koi some of which have 'almost' no black....it would be a short step for it to be none. There are some 'sunsets' in the batch, and there should be platinum paraibas too (but I can't see any).....so are the 'sunsets' actually koi? Pics and genetic info to follow......

Hi Graham,

First of all gold marbles can be either homozygous (Gm/Gm) or heterozygous (Gm/g), in general fish that are Gm/g have less black than fish that are Gm/Gm. There are other factors to consider too....

You mention that you're expecting paraibas....

In my experience gold marble ghosts tend to have less black than their ordinary gold marble siblings. This also seems to apply to gold marble blushing (ie Koi).

There has also been discussion on TAF II about the influence that the philippine blue gene has on the expression of pigments in general and black in particular. This agrees with my own experience that the pb gene reduces the expression of black.

Finally there is also evidence to suggest that the amount of black that is expressed is something that can be selected for.

So it's possible that both parents were heterozyogus for gold marble, in which case you would expect 25% sunsets, but I personally have had several gold marbles which could only be identified as such by the odd, very small, patch of black, and it is possible to have genetically gold marble fish which appear to be plain golds.

How old are the batch?, in my experience it can quite tricky to tell sunsets from sunset paraibas until they are 2 or 3 months old. Young sunset paraibas can look quite pinky/orange!

Hi Rob.
These youngsters are the grandkids of one of Kens paraiba koi
Sm/+ - Gm/Gm - S/S - +/a - pb/pb


and marble blushing..
M/g - S/S


This gave me (sorry for the order of codes)
koi... Gm/g - S/S - +/pb - +/a
koi... Gm/g - S/S - +/pb
koi... Sm/+ - Gm/g - S/S - +/pb
koi... Sm/+ - Gm/g - S/S - +/pb - +/a
marble blushing ... M/Gm - S/S - +/pb
marble blushing ... M/Gm - S/S - +/pb - +/a
smokey marble blushing Sm/+ - M/Gm - S/S - +/pb
smokey marble blushing Sm/+ - M/Gm - S/S - +/pb - +/a

The offspring types were as expected.

I chose these two koi, you can't spot the smokey or albino gene.





I now know they have a hidden albino gene and I doubt they have the smokey...so I'm guessing they're both Gm/g - S/S - +/pb - +/a

The albino fry didn't survive. The remaining fry are as expected but some of the koi are very pale. I was doubting the presence of the gold gene because I was expecting the platinums to be more visable. After doing the genetics I can't find a way of excluding the gold gene and still getting the phenotype ratios.......so I will have to keep these a little longer to be able to label them properly. I can just see hints of the ones homo for pb now, they do have an odd look about them.








I guess because the grandad and parents have very little black markings, I shouldn't be expecting much on the kids .

Neither parent is heavily marbled, so you shouldn't expect to see too much marbling in the offspring, those with the most black are probably the Gm/Gm fish, you should have 25% g/g.

Have you kept just the largest individuals from the spawn? If so, you may have inadvertently discarded most of the pb/pb fish.

I think the albino gene may also have a bit of an influence on the amount of black expression - just a hunch!