Personally, I don't count CGI hordes as characters. Plus, is it a story point that women aren't allowed in the "army" or is that an assumption? (Real question, I haven't seen it.)
I can't say that I'd freeze frame it to look for boobs, not that fish women should even have boobs but I would say that all the foreground characters seemed to be dudes of one species or another and all the soldiers and mercenaries with lines appeared to be guys.
I'm not really clear on Atlantean politics but it does seem to involve patriarchal absolute monarchies with no political institutions to reign in the individual monarchs beyond a council of monarchs requiring a majority to go to war, and with Queen Atlanta ceding all her power to her husband until she'd produced an heir to take over in her stead.
I would despair if I was looking for true equality on screen but I do think that writers and producers should be required to put more effort in than they used to. I was watching Winter Soldier and there is a massive male/ female imbalance in that movie but there are at least female agents, police officers, and seven female characters with lines, only one of whom is in the role of (ex) girlfriend.
It is possible to do a way better job than Aquaman did in terms of representation on screen. I get annoyed whenever modern blockbusters backslide this badly.