Tiny black line on Platy monopodium

[TashKoshBGosh]

Hi! I have noticed a recent appearing of a tiny black line on the gonopodium of one of my male blue and black Platys (see attached photo). I have been researching all kinds of worms, pests and parasites, and have found nothing that looks like this. Is it likely just a color spot appearing as he matures and colors up, or is there some pest I am missing that looks like this???

 

[DragonScales+Doubletails]

if this is the only fish watch his behavior closely. if he's out of wack you'll know something's up. but if others experience this you are in trouble.

 

[itiwhetu]

It looks like a color spot, don't worry, the fish looks like it is healthy.

 

[Colin_T]

nothing to worry about, just colouration on his thingy