I absolutely love gouramies! I have kept gold gouramies for years. Glad to hear you got three as they do prefer some company. That being said, I know the golds tend to be semi-aggressive to aggressive if the odds are lopsided. I've never had the sparkling ones but if you truly want to reduce the chance id see if maybe you could exchange a male for a female. There should be a difference between dorsal fins but given their size it might be hard to distinguish. For company, they get along well with corys and neon tetras in my experience, again with golds.