Several environmental constraints have been hampering the development of aquaculture, in both marine and freshwater environments. One of these constraints are Harmful Algal Blooms (HAB) which are caused by over 400 species of microscopic, pelagic and benthic microalgae. These HAB pose a threat to coastal ecology, biodiversity, human health, and economic activities. There is a global consensus that HAB have been increasing in incidence, severity and geographical distribution linked to human activities and climate change, and that these HAB are problematic for fisheries and aquaculture as well as human health. Indeed, HAB cause illnesses to mass mortalities in several aquatic animals, including shellfish and fish in aquaculture farms. They are as well producers of highly potent toxins that can affect humans via the ingestion of shellfish and fish that have accumulated their toxins through direct ingestion or via bioaccumulation and bioamplification throughout food webs, or via exposure to dissolved toxins in drinking waters and/or bloom water aerosols. In this presentation, we present our analyses of 30 years data of HAB occurrence and their effects on cultured shellfish and fish, as well as associated human sicknesses, based on available global data.