You can see the ovisipoitor (probably spelled that wrong) on the first fish, looks female to me.
Umbee are unusual in that the females tend to out compete the males for food when small, part of the reason why I think there is such a glutton of females around. I kept the middle sized of the three I bought and ended up with a male.
Right now it's just a crapshoot, with the odds stacked for female.