Biosorbents for wastewater treatments is one of the most widely studied techniques in environmental and bioresource research. A marine-derived Penicillium janthinellum strain fungus was used in this study to prepare self-immobilized mycelial pellets. Fe3O4 nanoparticles were added in the culturing media, which were automatically incorporated in the mycelial pellets during culturing process to endow the pellets with magnetic properties. These magnetic mycelial pellets were used as biosorbents for water treatments, and their morphology was characterized by microscopic observation, Energy dispersive X-ray analysis, Fourier transform infrared spectroscopy and thermal gravimetric analysis. The effects of nanoparticles in culture media on pellet formation were discussed and the content of nanoparticle in culturing media was optimized. Study on Congo red adsorption from aqueous solutions showed that the pellets with 71.6 wt% Fe3O4 nanoparticles had a maximum adsorption capacity of 102.4 mg/g pellets (360.6 mg/g mycelia), and the solution heated by magnetic induction showed faster adsorption rates than that of bulk liquid heating processes under the same adsorption temperature. These pellets were easily separated by magnetic forces and the magnetic induction heating is beneficial in energy saving when comparing to traditional heating processes. (C) 2015 Elsevier B.V. All rights reserved.