Although they are made up of Males and Females, they believe gender derivatives such as "Mister" to be insulting.
Their familial system is made of up family-clans, such as the P'Thall and D'Quas clans. Each family has special emblems denoting them, worn for ceremonial purposes on specially made tunics that a Kradian will wear to high-class events, similar to a dress uniform. Some higher class families are known for their business, such as the P'Thall family-clan, and their specialty in technology.
In the Kradian language, grelth is an insulting term.
In 2267, the P'Thall family took vacation on Versailles, after Daleel went to meet her love human Aaron Cole. Sahirn ended up murdering his daughter to protect the family honor, and frame Mr. Cole. Sahirn rejected extradition, and chose to be tried on Versailles when he was found out, to avoid more family disgrace.
Their skin is a bluish tint, and they lack circulation systems as well as sweat glands. They have "eye stalks", shooting out from above their eyes that are movable based on the mood of the Kradian, similar to Andorian antennae. (TOS novel: The Case of the Colonist's Corpse)