I have had great luck putting a very small maroon in a tank with a much larger maroon. Just recently I put a gsm F1 baby about 1 inch in with a 4" plus GSM that I had without a mate. The big one came over and head butted the little one once or twice, after that most everybody would call them "bonded" or "mated". I have heard you always want to put the little one in the bigs ones tank not the other way around. Otherwise the tiny maroon will try to defend it turf against and lose badly. Putting a way undersized maroon in with a large one sounds risky, but I've done it three times without so much as a skirmish. Its like the little one knows not to even try to fight, and submits instantly. And if your big one has been alone for awhile-it's def. a she-and should appreciate some "man-company"! Yeah, I'm sure people have a single Maroon that is as mean as cr@p, but I have worse battles with 1 cm maroon siblings.