Hi,
Thanks for the extra pictures.
I think that all the fish that you have posted pictures on in this thread are males. The last two are in their early teens.
There have been three different fish only?
I'll try and explain it visually.
Here is your smallest fish

- Your 3.5 inch
Here is a thin female of mine that is quite long

- My 4.5 inch
Here is your 4 inch "female"

- Your 4 inch
I have used this thin female of mine (pictures were when I got her) for this example because I know she is a female, rather than a dormant / sub dominant male, yet she could be a male if a: I didn't know she was a female, and b: she was about the size of your smallest one.
So what is the difference you ask.........
Well, if you look down on these three photos then your two have a different shape. The general shape of yours, as I see it, is that the head is quite broad. From the level of the eyes / Leading edge of pectoral ray, the body goes straight back across the pectoral fin, and then narrows on the way back to the tail. Generally the body is at its widest at about the gill plates. The odontodes on the posterior of the body are distinct and in straight lines.
The shape of mine is very similar except that I think the Body is still getting wider in the region of the pectoral fin, therefore the gill plates are not the widest point of the body. Also as my fish is "bigger" than yours I would expect to see distinct odontodes on the posterior of the body of some description if it was a male, especially since it was kept with other members of the same species at the time of the photo.
Also I have seen in the fishes "puberty" the bushy odontodes on the posterior of the body in males start out as distinct lines of odontodes which become more pronounced and wisker like as the fish matures.
The difference in the odontodes on the posterior of the body in males and females, is: The males are thick like facial hair on a human, and the females are like strands of silk.
The eyes of your ones are not sunken, so I think that they are healthy looking.
I hope this helps.
Cheers
Geoff