The study investigated factors influencing the choice of fish traders' marketing channel by fish trader and the determinants of their gross margins. A multistage sampling technique of 115 fish traders was used. Four key informants and two focus groups participated in the study. A Probit model was used to determine factors that influenced the choice of fish traders' marketing channel. Findings from the study revealed that volumes of fish traded per month, distance to market, membership to a fish marketing organization, payment mode, household size, presence of other sources of income were statistically significant in determining traders' choice of marketing channel. In addition, it was found that a formal trader on average sold 6.882 tons of fish whereas 2.095 tons of fish were sold by the informal trader per month. The study therefore recommends that Informal traders be clustered into a marketing organisation; through which they can be trained on business diversification, collective marketing, and group savings to ease access to credit. It is important to eliminate the challenges encouraging informal cross border fish trade by harmonizing regional fish standards, facilitating exchange and use of fishery trade information. Further, there is need to strengthen the data collection systems in order to have accurate estimates on the contribution of fish to trade and food security.