This study examines the socio-ecological conflicts and usage dynamics between shellfish farmers and small-scale artisanal fishermen in the Bizerte Lagoon, Tunisia. Using a qualitative approach based on ten semi-structured interviews conducted in 2026, alongside direct field observations and institutional analysis, we investigate the root causes of the structural tensions that culminated in a severe episode of vandalism in November 2019, where mussel-farming installations in Menzel Abderrahmane were systematically destroyed. Our findings reveal three primary dimensions of conflict: (1) a causal dispute regarding the origins of lagoon pollution, where fishermen blame shellfish farming for ecological degradation while farmers point to external industrial and domestic waste; (2) unequal institutional recognition, with both groups feeling abandoned by state authorities; and (3) a clash of incompatible temporalities between historical, traditional fishing rights and modern, long-term aquaculture investments. Rather than a mere material resource competition, this situation represents a profound conflict of recognition. We propose a shared governance framework based on marine spatial planning, collaborative environmental co-diagnosis, and the establishment of permanent multi-stakeholder mediation platforms to transition from destructive conflict toward sustainable, integrated coastal zone management.