How long have you had this WSM? At 1.5 inches he's still quite small and may be considered a juvenile, probably still a male.
There are quite a number of ways to attempt pairing them, but according to Joyce Wilkerson's book 'Clownfishes', the most reliable method is to ensure there is a significant difference in size of the fish you are attempting to pair. That way, the smaller fish is more likely to yield rather than fight to the death. So your options appear to be to wait until your current resident has grown some more and add a smaller fish, or attempt the introduction of a much larger maroon. This could be dangerous since your current clown is already hosting in its BTA and may be reluctant to yield when confronted by a larger specimen. He may be docile now, but just wait until he catches sight of another maroon. If you can get hold of a plastic veggie clip in the shape and colour of a clown fish, dangle that in front of him to guage his reaction.
From my own experience, I managed to successfully pair two specimens of approximately the same size. They were also fairly small, maybe 2 inches and apparently both still juveniles, that is neither had changed to female yet. This was probably more luck than anything on my part. As in your case, the resident clown was already hosting in a BTA in my 75 gal. tank. There were certainly some anxious days/weeks thinking I may have made an error. When I introduced the newcomer, the resident clown's white stripes actually turned grey it was that upset. Over the next few weeks there were many confrontations, but none resulting in serious injury to either fish. The newcomer would do laps along the glass near the surface during the day and in the evening managed to find a safe haven behind some rock work. He actually endured more harassment from a blue devil damsel in the tank than the other maroon. After about 3 weeks, things started looking up with the new maroon yielding to the resident with the familiar twitching and the resident slowly allowing him nearer the BTA. They're now a bonded pair, no spawns yet but the resident is easily twice the size of the male and much darker in colour.
If you can get another clown a little smaller, then you may be fortunate as I was, but there are no guarantees and you'll need to be prepared to lose one or both in the process. The only way to find out is to give it a shot. If you have sufficient hiding places, i.e. live rock, for the newcomer's safety, your chances of success should be pretty good. Some folks use separators or specimen containers to ease the pain and allow them to get familiar prior to setting the newcomer loose in the tank.
. My Question is about pairing it. I see lots of posts about trouble pairing maroon clowns. What's my chance with this one? Anyone have any ideas?
