Sex Check

How can one differentiate the sexes of fish? I figured this is a useful topic to start on.

We know that clowns (at least Maroons), can change sexes. Two male maroons of similar size are placed in a tank, the larger of the two will continue to grow, changing sexes, providing the female needed for the mated pair.

This is a start. I would like to know if this happens with other fish, if so which species?

And if not how can we tell the sex in those fish?

I'm interested in the Yellow Neon Goby. Does anyone have any ideas?

 

I couldn't find any info for a yellow neon goby but i did find info for a neon cleaner goby:
"They may be sexed with the examination of their genital papilla. Upon close examination, perhaps with a magnifying glass, males will show cone-shaped papilla, which come to a pointed tip, directly in front of their anal fins. Female Neon Gobies may not have any structures visible in this area, though sometimes, particularly around the time that the female is spawning, short, rounded papilla may be visible. "
NEON CLEANER GOBY

 

Fairy and flasher wrasses always have males with more elaborate finnage and brilliant coloration. Genus Paracheilinus and Cirrhilabrus.

 

Thanks a million Joe, very helpful info.

 

NO PROBLEM