Exploration of the perfect combination between metamaterials (MTMs) and plasmonics has paved the way of the new innovations in electromagnetic and communication engineering, especially in sub-THz spectroscopy. In order to contribute to such developments, plasmonic resonances in sub-THz fishnet MTM on the basis of complementary hexagonal resonator structure is investigated in this paper. The design, in which method of removing hexagonal structure is applied, has been performed based on finite simulation technique. Five distinct plasmonic resonances are determined at some of the specific frequency spots where interactions between electron plasmas and incident electromagnetic waves can be observed. The proposed material can be employed in several subtopics of electromagnetic engineering such as high pass filters and antenna applications. Furthermore, thanks to the THz wave confinement property of this plasmonic structure, incident THz waves can be controlled efficiently and therefore, the proposed MTM can be tailored at THz spectroscopy and imaging, localization of the THz wave and energy, sensors and photonics applications, effectively.