I don't believe that it makes any/much difference as long as the main goal of deterring cannabalism is acheived, especially when it comes to camoflauging any blood. I've never heard of any specific colors that are preferred over the other for any particular species. Although, a "black light" may not be recommended!
I've used a red 250watt on a dimmer, if it is turned all the way up and it is extremely bright, the BW's go wild and immediately become abusive to each other. My experience has always been, the darker, the better.
But I'm no expert, their all on the news channels.