It's normal for them to challenge each other occasionally, and they'll chase and flare at each other as well as females. None of it is overly aggressive in nature (they're a peaceful bunch), but too few females may cause excess stress. Bear in mind that WCMMs do better in colder water than most tropical fish; I keep my 36G at 72-74F which is on the high side of WCMM temperature ranges, and on the low side of the flame gourami I keep in there. They'll tolerate higher temperatures, as they're not wild-caught anymore, of course. My LFSs keep them at 76F.
I have a 20 gallon long. I have my 6 bloodfins, 6 female WCMM and 6 male WCMM. My bloodfins do OK but my male WCMM's chase and harass every one in the tank. My bloodfins stay more in the back because of my male WCMM's. I have removed all the males for now and placed them into a container temp until I hear from you. I do have a spare 10 gallon tank.
I keep my tank at 76°F my heater does not come on in the tank since I keep it set low.
I am still having problems with the WCMM.I have changed their tank to a 40 gallon with 12 Bloodfin Tetras and 11 WCMM. My WCMM are bothering my bloodfins by nipping them and chasing them constantly. My bloodfins don't come out much because of this.
I have removed all the WCMM and put them into a container temp by themselves. I need advice what to do with them now.
My Bloodfins seem much calmer and happier without these WCMM in the tank.
I did research on the WCMM and it says they only harass their own kind but that is not what I see in the tank.