I must've lucked out, My 1.5 year old ball was eating all white mice for way too long until I found a place that has cheap rats. The first rat was brown and white and he took it no problem. I also got mice from the same place that were different colors and my 5mo girl took an all brown one no problem. I had been feeding her all white ones the whole time I had her.. I'm sure I'll run into a picky one someday though