you can get one without the other.
the kribs are true albinos. they produce no melanin or any other pigment in the eye or the body. the belly's go redish pink but are not as red as in the normal non albino strain. but i think what we have is the end product of breeding fish with the recessive trait (aa,aa) with aa,aa and then selectively breeding the resulting off spring with aa,aa. I have seen pure white albinos with no pigment at all but that was a long time ago. so if the gene for belly colour is on another chr then its just fair pickings, and a case of one genes dominance over another.
But i don't think it is the same across all species as this would depend on the alleles, and where they crossover on the chromosomes. if the gene in question is sex linked then it makes life more complicated cause then you have to know everything about the sex chromosomes... and i dont know all about this fish's chr's. :lol:
if its not sex linked, then its on the autosomes, and i know nothing about this fish's autosomes either. :lol:
I would imagine each fish would be different, but across a species range there would be some commanilities observed.