Anchovies are amid the largest fish catch worldwide. The anchovy fillet industry generates a huge amount of biowaste (e.g. fish heads, bones, tails) that can be used for the extraction of several potentially valuable bioproducts including omega-3 lipids. Following the extraction of valued fish oil rich in omega-3, vitamin D₃ and zeaxanthin from anchovy fillet leftovers using biobased limonene in a fully circular process, the solid residue was used as starting substrate for the production of biogas by anaerobic digestion. The results first reported in this study demonstrate good potential energy recovery of the anchovy sludge of about 280 mL_CH4∙g_VS^-1. Due to unbalanced C/N ratio typical of marine biowaste, co-digestion with a carbon rich substrate is recommended.