As I'm thinking about it a 25g tank is a high tank rather than long (struck me as I turned around and looked at my 25g refugium lol) and the angel and clown will both become medium sized fish, and the anemone will take up a bio load. You may consider that all fish wise and think about some inverts. You can add some of the more fun ones like a sally light foot crab, an emerald crab, a coral banded shrimp as long as you dont add any small fish or corals. People will say those inverts are reef safe but it's really hit and miss. The other fish I was thinking about was a flame hawkfish but I havent personally had one and I know that there shrimp eaters, not 100% sure about if they would eat crabs though, and I seriously doubt they would bother a coral banded shrimp. If you were to add one it would give the tank nice coloring. Clown fish - orange, flame hawk - red, coral beauty - blue/purple, anemone- whatever color you get. That is if your thinking about it colorwise. You should consider adding a protein skimmer if you add the 3rd fish.