Sexing Banggai Cardinal

[Zakary2003]

I bought a pair of young banggai cardinals three days ago, but one of them died suddenly. It got sucked into a powerhead and beaten up (idk if it was postmortem or perimortem), so I can't tell if it was the male or the female of the pair. The store sexed them for me, so I'm not even sure if they were opposite sexed, but I was hoping the brilliant minds of reef2reef could help me determine the sex of the one that remains so I can try my best to get an opposite sexed replacement. I know it's hard to tell as juvies, but I took a lot of pictures so hopefully at least one will be clear enough.

If I can't sex this one, should I try getting an unsexed fish and hoping it's the right sex, should I get a pair and have a trio until two pair up and rehome the third wheel, or should I take the healthy one back and see if they can give me a new pair of cardinals?

I was really looking forward to potentially breeding banggais because I came from the freshwater world where live bearers and mouth brooders are common and raising fish is super easy, and I miss that in my reef tank.

 

[Stigigemla]

If you put it upside down in a net it is possible to see the genital papill just in the front side of the anus.
There are pictures somewhere on cichlid forums that describes it much better than text.

 

[Kmst80]

when you give the bangaii a lot of food at once it could show 2 black openings on underside if a female. Male will only have one. Not bulletproof. Some ppl reckon they can tell by the jaw, males being bulkier.