Zebrafish and steroids: What do we know and what do we need to know?

► Zebrafish is a model organism in developmental biology and endocrinology. ► We review the research on steroidogenesis, the action of steroid hormones, steroid catabolism, and endocrine disruption. ► Some aspects of steroid hormone research, e.g., expression patterns of the involved genes, are well characterized. ► Enzyme functionality, steroid elimination, and the steroidal impact on development or sex differentiation need research.