If it makes you feel better, it was only this week that he finally colored up a bit. Previous to this, I’ve just seen a hint of maybe a different shading in the fins, but nothing that was certain. Just enough to tell it was probably male.
Though, now he looks more like Bintan “blue line”. Except that lighter ring in his tail which may turn out to be a different color yet. I don’t think he’s mature yet, he was continually approaching another fish in the tank and turning sideways and so on (if that’s even courting behavior and not aggression) but this was the brightest he got and didn’t stay like this for long. I didn’t risk the flash on the camera because I figured that would be the end of seeing any color from him for a little while. There is one larger plain striped one in the tank which I assume is female. But, oddly, her stripes are much wider than the others stripes. Either perhaps that one is more mature, or a different Paro mixed in. I don’t know.
I was going to ask if the ones you got in were showing color. I’m tempted to just order all the Paro’s they have and hope for the best. But, I keep catching myself from starting too many projects at once.