I concur with most of what was said above. As long as you don't put two females together, however, unless one is markedly weaker than the other, you should always end up with a pair. (Johnny, Maroons are a bit different in that regard, and it's best to just buy a mated pair).
I've had my pair for almost 2 years now. They were about 4 months old when I got them (tank raised, most likely brother and sister)....well they were brother and brother when I got them

, now the female is about 3 times the size of her mate. I've not seen them spawn, but I see them doing the shimmy together

IF they have spawned, I'm sure the eggs would have been dinner for my Coral Beauty who is forever hanging with the clowns, I think he thinks he's a clown.
Tomatoes can get big, so yes a larger tank might be in their future, however I've noticed that my pair stay in their corner. They live in a LTA that I bought from another hobbyist. The male never goes more than 6-8 inches from his little depression in the rock behind the anemone (and I'm always looking in that depression for eggs!) and the female goes a bit further away, but not much....perhaps 12 inches. She keeps every grain of sand OFF her space on the bottom of the tank, and she gets very upset if sand gets wafted back into her space by an engineer goby! She spends many hours fanning the sand and cleaning.
I'm sure they will spawn eventually...everything here that comes in pairs seems to do that in my house.
Jenn
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