Deep‐diving surveys enable observations of new features of behavioural and functional dimensions of the fish that are typically missing from specimen‐based taxonomy. This study documents three rare armoured searobins (Peristediidae: Scalicus engyceros , Paraheminodus murrayi , Peristedion liorhynchus ) in Xianbei Seamount, Zhongsha Islands and Shenhu Canyon in the South China Sea. Not seen in the dead specimen, the fish in lif...