There are always a few fish around. I try to have the whole thing focused on aquaculture, since that is the main goal of the FFM, so you do see some clowns, and a few others, but it is mostly coral. I know I will have a few designer clowns in the raffle from Sea and Reef, for example.
That said, there are a bunch of stores coming. If you are looking for something specific, you could try to set something up and pick the fish up at the FFM if you want.