Effects of four CeO2 nanocrystalline catalysts on early-life stages of zebrafish Danio rerio and crustacean Daphnia magna

► Effects of CeO2 and CuO-CeO2 mixed oxides on daphnids and zebrafish were studied. ► Pure CeO2 induced no effects, but CuO-CeO2 sub-lethally affected fish. ► Only mixed oxide with 20% Cu content affected the survival of daphnids. ► The effects could not be linked to specific physico-chemical property of material. ► Further studies with functionalized nanomaterials are recommended.