We ate at Coral Reef as part of the Candlelight Processional Package. The Chef made me a special vegetarian dish of rice and vegetables in a delicious sauce. The menu may not necessarily have a vegan dish, but usually the chef can make something pretty good out of ingredients that they have.
For lunch one day we went to the Coral Reef restaurant at Epcot. I had made reservations here when I was still eating meat (but had since gone vegan) and unfortunately the one vegetarian dish was not able to be made gluten free, so I had to get fish. Blech.
It is certainly weird eating fish, while enjoying the presence and beauty of a fish tank.