Toxicological effects of the widely used flame retardant, tetrabromobisphenol A (TBBPA) were assessed in a partial life-cycle test with zebrafish (Danio rerio). Exposure of adult fish during 30 days to water-borne TBBPA in nominal concentrations ranging from 0 (control) to 1.5 microM was followed by exposure of the offspring in early life stages up to 47 days posthatching (dph) to the same concentrations. Adults exposed to 3 and 6 microM showed severe disorientation and lethargy shortly after beginning of exposure and were euthanized. Because semistatic exposure resulted in fluctuating water concentrations, pooled fish samples were chemically analyzed for internal dose assessment. Egg production was decreased in fish exposed to TBBPA concentrations of 0.047 microM and higher, and a critical effect level of 7.2 microg/g lipid with a lower 5% confidence limit of 3.9 microg/g lipid for 50% decreased egg production was calculated. Histology of adult ovaries indicated a relative increase of premature oocytes in two surviving females exposed to 1.5 microM. Hatching of TBBPA-exposed larvae was decreased except in animals exposed to 0.375 microM. In the highest exposure concentration, early posthatching mortality was high (81%) in larvae and the surviving juveniles showed a significant predominance of the female phenotype. Exposure of eggs from control parents up to 6 microM TBBPA resulted in increasing malformation and pericardial fluid accumulation from 1.5 microM; at higher concentrations, all embryos failed to hatch. The presented results indicate decreased reproductive success in zebrafish at environmentally relevant TBBPA concentrations.