Hi, just want to start to start off with saying great site, Ive been flicking about for quite a few years now but haven't had a question until now
Anyway could someone please id this little cory catfish? He came in with a batch of Corydoras aeneus . He was in the shop around 3weeks and stayed this colour and now Ive had him for a few days and still no colouring up now so I assume he is this colour....
Looks like a xanthochromistic specimen of C. aeneus. Contrary to albinistic specimen who have unpigmented (red) eyes, these do have black pigmented eyes. Don't think it will ever get coloured.
He (she) is a beauty. If you bred from him (her) would any of the offspring have the same lack of colour pigmentation? If so it would definitely be worth trying to breed as I am sure there would be a market for a little stunner like that
according to Medelian rules, its offspring would have for each and every feature 1 gene from this one, and 1 from the othre parent.
If that parent would be a normal Cory, all new geneswould have to compete with a normal one, which mostly would dominate. A geen for green vs a gene for no color what so ever would result in somewhat less green, thus a normal colored Cory.
However, breeding with this offspring, which would all look alike, should result in xantoristic Corys. Depending on the amount of changed genes involved in producing the color the amount could be 1/4th (1 gene) or 1/16 (2 genes) or 1/64 (3 genes) et cetera.
However, if you happen to find another one, and have a male and a female, you could hope te breed them true.
Still, it could also result in normal corys. Think for instance about this system:
Something [gene a] Something else [gene b] green color
If 1 cory misses gene a, it will not get green. If another misses gene b, it will look similar, but breeding would result in offspring with gene a (from dad) and gene b (from mom) thus a green cory
Again, the grandchildren (F2) would get whitish again
Thanks for the detailed reply Bas Pels. Someday I need to get my head around genetics - very interesting. Still think that this is a lovely fish and well worth trying to pair up.
