Determination of safe doses of ozone to use for fish egg disinfection: the case of Atlantic cod (Gadus morhua)

The disinfection of eggs by direct exposure to ozonated water is of particular interest as a means of ensuring disease-free eggs without the use of harsh chemicals. However there are numerous knowledge gaps including safe contact times, exposure levels and long-term effects on Atlantic cod. The effect of different ozone doses (0.5-1.0, 1.5-2.0 and 2.5-3.0 mg O-3/L for 1.5 min) was tested on recently fertilized Atlantic cod eggs vis-a-vis the commercial disinfectant Perosan (TM) (0.004 mg/L) and an untreated Control (similar handling and husbandry) on larval nucleic acid concentration, hatch rates, growth, and survival. Overall, our study shows no negative effect/toxicity of ozone treatment at < 3.0 mg O-3/L for 1.5 min on cod eggs and/or larvae up to 30 dph.