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The tolerance of striped trumpeter, Latris lineata (Bloch and Schneider 1801) embryos to ozonated seawater was examined as a possible means of disinfection. The effect of a range of ozone doses and exposures (CT = concentration · exposure time) was tested at different stages of embryonic development. Three-day-old embryos two-thirds developed around the yolk were exposed for 0.5, 1 or 5 min to ozone concentrations of 0.5, 1, 2 and 5 mg O 3 l )1 in a fully orthogonal factorial design. For each treatment there were four replicate 250 ml containers that each received 100 -15 embryos. There was no significant difference in hatching success between control-treated embryos or embryos ozonated at 0.5 or 1 mg O 3 l )1 for 0.5, 1 or 5 min (P < 0.05). However, hatching success was significantly reduced when embryos were treated with 2 or 5 mg O 3 l )1 for 5 min or 5 mg l )1 O 3 for 1 min (P < 0.05). The tolerance of embryos to 0, 0.5 or 2 mg O 3 l )1 for 1 min at different stages of development (Day 0, 1, 2, 3 or 4), was then examined. An ozone concentration of 0.5 mg l )1 had no effect on hatching success at any stage of development, but a concentration of 2 mg l )1 significantly reduced hatching success on all days except Day 3. A safe and tested hatchery practise is to disinfect striped trumpeter embryos with 1 mg O 3 l )1 for 1 min on Day 3 post-fertilisation when the embryo is two-thirds developed around the yolk.