There are completely Black Chickens that have black plumage, black legs and nails, black tongue, black meat and bones, and even black organs.
Kadaknath chickens originate from India and are some of the most popular black chickens in India. Kadaknath chickens are completely black birds. They have black plumage with greenish iridescence. Their beaks, wattles, combs, legs, and tongues are all black. Apart from their meat, these chickens have black organs.