I'd like to take a shot at answering this question. Like you ohcustoms I've been breeding cons for a very long time. 21 years to be exact :lol: My first breeding pair was when I was eleven. It was a male pink and a female black or grey convict. ( I tend to call the regular old striped ones grey convicts) Needless to say they spawned in my 15 gallon and it may have been the coolest thing I'd ever seen. My Dad bred angels and sea horses but I never paid attention :lol:
At any rate, the spawn resulted in some pink, some grey and some marble. To my Dads and the local pet stores knowledge they had never seen them before and both told me they wouldn't be worth much so I ended up feeding them to my brothers aligator gar :lol: Big mistake apparently :lol: Fifteen years later I was in a lfs and saw them for sale for 12.99 apiece and I almost died :lol: Grant it this stores prices always run high but you get what you pay for in my opinion. It was then that I decided I was going to make my own marble con like I had done in the past. My theory was that I needed to start with a pink male and grey male and see what happens. Well as you can guess nothing happened so I decided to do a little experiment. I decided that I'd slowly, generation after generation break down the grey gene. Well it worked... I think. Here's my story... I was doing water changes and at the time I didn not use lids on any of my tanks and I think a male popped over to the current breeding pairs tank and spawned with the female. Funny because all my tanks are painted for comfort of the fish so how did he know if he jumped he'd get lucky?? The result was a few marble fry from that spawn but I don't know if it was the male that jumped in who fertilized the eggs or the male that was with her.... :x Problem was I had know idea of the jumping males background or lineage :x That was almost two years ago now and since then all convict experiments have been haulted due to my sons being born and not having a lick of extra time. Not to mention the adiction to this website.... Curse you C-F!
Here's the problem. No one knows if pink cons existed in the wild before the seventies simply because all anyone ever says is they were "developed" by two gentlemen??? What the heck does that mean??? Now the problem is pink convicts do exist in the wild and so do marbles and they could care less who they breed with as long as they can breed. Some day, probably 10 years from now I will start experimenting with cons again but not until I've got more time... which will probably never happen :lol: At any rate I have come up with a con that rivals in color to an HRP and I still have the female that I talked about in the begining of this marathon post. I've also got one of her sons.... Some day... Some day...
So in short (besides frameshifts interesting point) I do believe you can get marbles from breeding a grey convict with a pink. But the grey has to have a reccesive pink gene that been bombarded by generation of breeding it in to it.
What I mean is to do this:
GF = grey female
PM = pink male
PMRG = pink male with reccessive grey gene
GFRP = grey female with recessive pink gene
GF X PM = GFRP
GFRP x PM (her father) = GFRP times two now
GFRP times two now x PM (her grandfather) = Some marble, some grey (very few) and mostly pink.
You follow? Problem is I can't prove it. The other problem is how do you get prove pink and grey convicts, meaning there's no way to know their lineage since everyone breeds them and lots of stores take the fry....
Basicly at this point it's going to be luck of the draw when trying to come up with marble cons. That's the short answer :lol: :lol:
Here's a few shots of mine:
This is a male as a result of the spawn in question:
This is a female with pink reccessive gene twice over if you get what I mean:
This is her daughter after spawning with her grandfater who was pink:
The (what I like to call electric blue convict or poor mans HRP) will be spawned with a male pink to see what comes out of it and she will also be spawned with the male marble that's pictured here for the fun of it...
I hope this helps in your quest but I doubt it