Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the efficacy of copper(II)‐betaine as a nutritional additive for all animal species and on the safety for the marine sediment when the additive is used in sea cages. The FEEDAP Panel concluded that the risk to the marine sediment is acceptable when the additive is used in sea cages. The additional statistical analysis of the results of the efficacy study already assessed in the previous opinion did not allow the Panel to conclude on the efficacy of the additive.