4cm long including tail means they are still a bit on the young side to sex, but looking at the top picture in particular, the body profiles indicate you may have a mix of both. No guarantees at the moment though!
There are none that are obviously female. Feed them well for the next few months, plenty of live food and so on, and the female shape should become much more obvious.
Second option if you are more impation, study the shape of the fins underneath. Girls have paddle fins, guys have pointy fins, but this is much more difficult to see generally.
I think the bottom right fish in the first picture is male but as others have already said, it will be a lot easier to tell in a couple of months. The rest of them look like ????? to me.
Did you work it out? I hope you can get them to breed, as they are great fish! I have 8 of them myself.
If we both have offspring, could we do a trade of the offspring to prevent inbreeding. Would love to breed some high quality second generation tank bred gossei.
They are not breeding.
I've placed them in separate tank, but soon I'll need it for fry.
Non of my corys are breeding, except sterbai.
One laser green female, like exploding, but not laying eggs and spending time far from main group.