The board discussed the issue at its September meeting in Cromwell but its opposition came too late, as the New Zealand Conservation Authority had already given its approval.
At a meeting in Beaumont on Friday the board resolved to write to the authority to express its ''strong disappointment''.
Board member Jim Williams said he was feeling ''pretty aggrieved'' with the authority's decision.
''The conservation authority moved ahead and made a decision, ignoring the [Otago Conservation] Board. We had an issue that we wanted resolved.''
The issues were around the potential for people to transfer the fish to other water bodies and a fish biologist's suggestion that a fungus the carp carried could affect native galaxiids.
Board member Iris Scott said there might be some benefits from the fish but more information was needed on other effects.
She said the aim of releasing the fish was to control grass growth, and that might have a positive effect on native galaxiids.
The letter to the authority will also ask for the information on which it based its decision to allow the release.
''It just seems like a huge leap of faith that the carp will stay in the waterway that they were released into,'' Dr Williams said.
Board member Francie Diver said there was nothing to stop people picking the fish up and moving them to another waterway.
