Fisher-trader relationships (FTR) encompass a wide range of influential and informal relationships that are present in many small-scale fisheries (SSF) worldwide. FTRs' potential to establish and maintain informal rules (FTR rules) that affect the resilience of fishing practices has shifted them into focus for formal fisheries management. Linking formal management rules to the landscape of informal rules requires a better understanding of fishers and traders’ role in rule-making and types of informal rules related to fishing practices. Here, we map out the informal rules related to fishing practices in Indonesia, Spermonde and compare them to formal fisheries management measures. We further assess fishers and traders' role in shaping certain fishing practices from which we draw preliminary conclusions about how and when formal fisheries management should involve fishers and traders. We find that FTR rules in Spermonde relate to a diversity of fishing practices and correspond to formal fisheries management measures such as in- and output control, temporal and spatial management. The emergence of fishing practices are linked to multiple functions within the FTR and to the network of relations of fishers and traders with other groups. These external relations are primarily served by traders. Thus, we argue that a foundation for linking formal fisheries management and informal rules exists on the basis of their similarity. Understanding the multiple functions and networks of relations can help identify intervention points for building or breaking resilience of fishing practices in Spermonde and beyond.