One of my clowns disappeared without a trace a week ago. His tank mates were another clown, a six line and a royal gramma. They all lived together peacefully for over a year. So now I am looking to replace him with preferably a colorful fish that could hold it's own without being over aggressive and swims freely in the water column. I really like a neon Pseudochromis, any other suggestions. It is a 25 gallon btw.