Don't know if it spawing, usually the water will become a little cloudly, don't know if putting another one in there what the out come will be, good luck.
_________________ what causes inflation
Yep, that's what a male Fungia looks like spawning. One can really make the entire tank milky white. I had four mass spawning at one time and it was a nightmare!
Turn off your skimmer in the meanwhile. After it's done spawning, use polyfilter and do some water changes.