convicts-pink/black expirment

My genetics is FAR from the best but I don't think by simply mixing the two you are EVER guaranteed marble. Marble I would think is a color trait that one must possess the gene for, but then again like I said my knowledge of genetics is limited at best.

Honestly it depends if the genes are dominant recessive or codominant etc... If you can tell me if one of them is dominant or recessive then I can tell you. I suspect the black to be dominant as is common in which case you wont get the marbled color by a simple cross

from what I can tell the marble gene is a highly recessive gene. you cant just put one black and one pink fish together and expect convicts. it could be that neither of these fish even carry the marble gene to begin with.

it seems the only sure-fire way to get marbles is to get two who obviously carry (eg, express) the marble gene and breed them together. you will get mixed fry out of them, for sure, but you'll probably end up with a few marbles out of the bunch.

it would take highly selective line breeding to attain anything close to a true marble line, IMO. a long term and very expensive comitment.

if you're serious about it, you should start looking around for someone with a stable marble line, and try to get a few spawn siblings.

or find at least 2 convicts that both definitely carry the marble gene.

what moonstream is saying though is mixing the two of them even 100x will never produce what your after... the marbled gene is something recessive that only one expressing it (res x res) would have. It is almost certain that you wont get the cross because BOTH the fish would need to have the genes in them (Dom x res) which wouldnt show it but would carry it and then would need to cross with another (Dom x res) to have a 25% chance at having a (res x res) baby (what you want). It is impossible to tell if the fish you have have the gene because they dont express it and the dominant one covers it up. It wont just appear by mixing the colors, what will likely happen is you will get a duller version of the parents or you will just get mixed batches of what you have now.