Hazards of Keeping Freshwater Fish in a Container that was Used for Adipic Acid I have an Intermediate Bulk Container (IBC) which is a large 3' x 3'x 3' plastic cube. The label on the container described it as storing Adipic Acid. 

Is it safe to use this container to grow plant life and harvest fish life for aquaponics? Or is there a possibility that this acid has leached into the plastic?

My quick research has shown that adipic acid is a mild skin irritant.
Adipic acid occurs naturally in beets and sugarcane, common foods, so it is not likely to be very toxic to fish if sufficiently diluted by washing. As @DGS and @ghost state, normal cleaning of the container followed by adjusting the pH for the fish should be OK. If you need to use an electric in-tank heater, though, check that it is safe to use in a plastic container.