Use of a thiamine antagonist to evaluate the effects of thiamine deficiency on lake trout embryonic development

► We assessed the secondary effects of thiamine deficiency (TD) on lake trout embryos. ► Oxythiamine (OXY), a thiamine antagonist, was administered at fertilization. ► OXY affected yolk sac utilization and caused reduced alevin length and weight. ► OXY concentrations causing secondary effects were associated with low EMS. ► Occurrence of EMS in TD-affected stocks is high so secondary effects are probable.