There are many peaceful wrasses. Lunar isn't one of them. As you found it. The 6 line in a 220 should be fine with most fish but firefish aren't one if them. They are too timid. I would add a few more fish to your tang spread out the aggression. Just make sure it's fish that can hold there own. Tangs , dwarf angels , blue throat tigger Fish like thst
Firstly, let me be very clear that I don't disagree with your statement.
I knew what to expect with the Lunar and it did go into an aggressive system. I had to remove it because the trigger, being the peacekeeper, was trying to tear it to shreds for being the most obnoxious fish in the tank- I saved that fish from itself and it cost me in stress and time.
I realize that firefish are timid but my clowns aren't in any way timid and they are bigger than the wrasse. My sixtine IS a problem with my clowns. This stupid fish has even tried to take on a much larger tang and continues to do so occasionally until he gets the scalpel. While I agree that adding a small wrasse with the 3 larger firefish was my error, and it wasn't a problem until many months later, there is still increasing aggression towards ALL fish in my tank. I feed well and have lots of hiding places in my rockscape so it isn't a matter of starvation or being forced to run into each other constantly. With this being the case, all wrasses are banned in my world regardless of their disposition, peaceful or not, due to my experiences.
Maybe it's my loss but I really don't care at this point and the 3rd time will not be the charm.
The purpose of my post was to inform the OP of my experience with my sixline.
I've read plenty of posts saying things such as "model citizen", "no problem with previously established and/or larger fish", and "always add last and you should be fine"- I can dispute every one of these statements through my personal experience with THIS particular sixline.
On the other hand, I've read plenty of complaints of increased aggression over time which is exactly what I have experienced.