6-line wrasse would not be good since you got a Dragonet in your tank. A few years ago, i got a pair of Mandarin Dragonet and a pair of 6-line in my 400 g tank. They are all had plenty of food and the Dragonet spawn regularly. After a long while, more than 1 year, the 6-line pair take turn and peck the eyes out of my Mandarin female. Once the eyes got peck out the attack end. The Mandarin starved after a few months and the 6-line goes to the LFS as soon as I caught them One right away and the other took 1 week with a fish trap.
So 6-line and Dragonet is a no no IME, especially in such a small tank