Abstract
Cognatishimia activa, previously known as Thalassobius activus, has been frequently isolated from marine environments. Here, we present the complete genome sequence of C. activa strain SOCE 004, assembled from the phycosphere of a long-term laboratory-maintained culture of the diatom Skeletonema tropicum. The complete genome is 3,211,994 bp long, with an average G+C content of 53.69%. The genome contains 3,195 genes, including 3,133 protein-coding genes, 50 tRNAs, and 3 copies each of 5S, 16S, and 23S rRNA genes.