All joking aside, if you mean coral skeletons (live rock), then yes, it will spike ph and calcium in the water. Cichlids and other fish that don’t mind the higher levels will be fine. But other fish like discus and soft water fish will not tolerate it as well. Also, the rough texture of the coral skeleton presents a danger to fish that rub against objects in the tank. Same goes for skittish fish that dart around the tank when spooked.
But if you mean live corals, then no. They will not survive in a freshwater system.