And yeah you could get 2 firefish since they are like cardinals, very calm, and stay in one area usually but id say no on the clown unless it is a MUST HAVE! I said to get 2 firefish becaus3 they do like to be in pairs. Whenever I saw them diving in australia, they were always in pairs!!
Also make sure to have a complete canopy top due to the firefish. They can and will jump out if not fully covered