A little addition help

I am looking to add another fish, I have a 6 foot 150 gallon tank with s&s puffer, Koran angel, yellow tang, maroon clown, algae Blenny, and yellow spot goby, any ideas on what I could, should add, I have looked at wrasses and another mandarin, I have pods everywhere in this tank, maybe something that eats pods would help too...I would like to look at the tank and see something active, that doesn't just sit on a rock till feeding time