Few studies have focused on marine resources from an archaeoichthyological point of view in the medieval and modern Mediterranean. This paper will present the preliminary results of one of the sites included in the corpus of a doctoral project on consumption and acquisition of marine resources in Provence (6th-17th centuries). Located on the shores of the Gulf of Fos, integrated into a complex hydrographic network combining numerous brackish ponds, marshy areas and the mouth of the Rhone River that has fluctuated over the centuries, the Habitat Mistral site at Fos-sur-Mer (13) was the subject of programmed excavations in 2000-2001. Fish remains were discovered in 105 stratigraphic units divided into 3 zones (zone 500 (US 17): 11th-14th century, zone 700 (US 53): 11th-14th century, zone 800 (35): 11th-14th century). This discovery makes it possible to envisage an archaeoichthyological study to explore the practices of acquisition and management of marine resources in one of the most important localities of medieval Provence. The drawing up of faunal lists and the study of anthropic traces of the various US have made it possible to identify differentiated places of treatment, storage and consumption. The biological profiles of the main species present show a selection of large animals in all areas and whatever activity at the origin of the deposit. In terms of acquisition practices, the exploitation of varied environments is suggested by the identification of both marine and freshwater species in the archaeoichthyological record. A survey of textual and iconographic sources suggests a location for these different environments and identifies potential local practices (dams and fisheries). The study of archaeological objects related to fishing techniques, found in situ, suggests the joint practice of net fishing and line fishing. Finally, the analysis of the carbon and nitrogen isotope ratios of the bone collagen of a sub-sample of 78 remains (6 taxa) confirmed the exploitation of multiple environments and refined the identification of the living environment of certain ubiquitous species.