Welcome, Jim,
I tried putting my male betta(who just died after about three years) in my 20 and he went after everthing; male, female, gourami, otocinclus, kuhli. But thats just mine. Some keep several male gouramis together with no problem. I have two red neon male DGs in with 4 powder blue female DGs and there was a little chasing a flaring but no fin-nipping or other damage. And since I added the 6 white clouds everone seems to be getting along.