Background and aim: The aim of this study was to analyze the descriptive and content structure of scientific outputs produced by fisheries researchers of Iranian universities in the Web of Science (WoS) from 1990 to 2020. Material and methods: This scientometric study was performed using co-word analysis method. The population of this research consisted of 1755 fisheries documents, published during 1990-2020 and indexed in the WoS so that at least one of the researchers had organizational affiliation with Iranian universities and research centers. The data were analyzed using Excel, and the thematic maps of this area were drawn using VOSviewer. Findings: The findings showed that Iran was ranked 25th in international fisheries scientific outputs; in this list, the United States, Japan and Canada were ranked first to third in the world, respectively. Moreover, the findings indicated that Iran had the highest number of scientific outputs in 2017. Among the universities and research centers of Iran, Islamic Azad University, Tehran University and Gorgan University of Agricultural Sciences and Natural Resources had the highest rate of scientific outputs, respectively. The researchers published the most documents in the Iranian Journal of Fisheries Sciences, Journal of Applied Ichthyology and Aquaculture Research. In the study of the co-word network analysis of Iranian fisheries, 10 thematic clusters were identified. Conclusion: Social network analysis of word concepts has suggested that the highest centrality indicators of fisheries studies is associated with marine biology, aquatics reproduction, aquaculture, aquatics safety system, quality of food products, pathogens in aquatics, pollution of aquatic environments, physiological indicators of stress, aquatics nutrition and salinity stress.