What causes the deeper black coloration in BC? Mine are not usually this dark.

Is it seasonal, environmental, other?



They are usually in shades like these.

BCP males will get very dark during spawn much like the lepomis species like BG, etc will during nest caretaking. I'd bet you caught a male off its bed and that the BCP are spawning or will soon be spawning in your pond.

Agreed. Spawning Male Black Crappie. Interesting note, even a spawning male White Crappie will turn darker during the spawn.

Tbar
You are fortunate to have a good supply of BCP. I have been trying to get a batch going in my 6 acre pond but the big LMB keep eating them faster than they can spawn. The BG have also added to the problem by nest robbing the BCP and LMB

Tbar, I have seen the males even darker then that during the pre-spawn and spawn, I will have to see if I can dig out some pics of some.