Guiding the sustainable development of sectors within the blue economy is critical not only to the global goal of thriving life under water (SDG 14), but also across many other goals related to resources, poverty, health, equity and wellbeing. This is especially the case for island and coastal states, where oceans support daily subsistence, livelihoods and economic opportunities, in the face of poverty and food and nutrition insecurity. The diagnostic framework for equitable mariculture development in the Western Indian Ocean will be a useful tool for people involved in coastal management decision-making, as well as mariculture planning and policy. It will help decision-makers in evaluating and guiding future mariculture initiatives towards a more equitable future, in line with mariculture development aspirations of a country or region.