Rapid cellular assessment of cell-cycle perturbation can complement conventional developmental toxicology in zebrafish, but rapid DNA-content workflows developed for mammalian tissues require adaptation for whole embryos. Here, we applied an embryo-adapted version of rapid DNA-content flow cytometry analysis within a 96-h cisplatin exposure model in zebrafish (Danio rerio) and integrated this cellular readout with morphometric, cardiac, and neurobehavioral analysis. Dechorionated embryos were exposed to 10–400 μM cisplatin and evaluated for body length, eye surface area, heart rate, locomotor activity, thigmotaxis, touch-evoked and vibrational startle responses, and whole-embryo cell-cycle distribution. The adapted workflow combines immediate mechanical dissociation, filtration, brief propidium iodide/RNase staining, singlet gating, and direct flow cytometric acquisition. Importantly, each flow cytometry sample consisted of a single embryo, enabling DNA-content analysis at the individual-embryo level without pooling. Cisplatin produced time- and concentration-dependent growth effects and high-dose behavioral alterations, whereas heart rate was comparatively preserved. Flow cytometry detected the clearest cell-cycle redistribution at 400 μM, with a significant reduction in G0/G1 and an increase in G2/M. These findings demonstrate the practical applicability of a combined rapid embryo-adapted DNA-content workflow as a complementary cellular endpoint in a zebrafish developmental-toxicity platform and support further methodological application across experimental settings.