Ill Rooster, Dark comb/lethargic
Edited by skiidevil - 12/6/15 at 7:27pm
If it was coccidiosis, treatment may have started too late.
Severity/rapidity can vary from bird to bird and depend on the strain of cocci.
It also could have been something else entirely.
Can you get a necropsy done? That would provide you some answers and perhaps help in the event you have other birds become ill.