My prized male Betta splendens, Obsidian. He is the very first truly black betta I've ever come across, and when I saw him I had to have him. He it utterly black except for the very tips of his ventral fins, which are white (which is true for almost all bettas).

Obsidian is a black lace super delta plakat betta. His tail shows flashes of either white or creamy blue between the supporting rays when the light hits at the right angle, and his pectoral fins are transparent with black rays and edges.