We have two black bunnies, and I have struggled to get good photograph. The photo above shows Stanley who is a very dark black bunny. He was hanging out in basket, which they bunnies find to be quite cozy.
I initially tried to photograph them in available light, and despite the fact there is a large window in the room, but I found the photos blurry due to slow shutter speeds. Had to switch to a flash. The basket came out overexposed and the bunnies were in shadow.
In Lightroom, I pushed up the saturation to get some color back in the basket and I burned in the bunnies a full stop.