Fish trade on Mafia Island involves several players in the value chain from fishing to the plate, either on Mafia Island or mainland Tanzania. This paper investigates the different actors in the value chain to establish how much each of them invests in the process of adding value to fish as a traded commodity, and how much they gain from it, with the intention of establishing who are the winners and losers in the fish trade. The results showed that small-scale fishers in Mafia are mostly on the losing side, spending long hours preparing for and undertaking the risky activity of fishing in rudimentary canoes, plus the cost of maintenance and the acquisition of their fishing gear. Due to their disadvantaged position and lacking the necessary facilities for the preservation and storage of their catch, they are forced to sell it at low prices in prearranged market arrangements to avoid spoilage and, therefore, incur loss. The findings of this study indicated where a major policy change would improve fishers’ welfare. Arrangements need to be made for small-scale fishers and female fish vendors to access markets to improve their gain at most fish landing and trading sites. This would help to reward the hard work and risk taken by fishers and women fish vendors, and reduce their poverty.