Black molly isn't.

[G2-B]

I noticed that one of my black mollies isn't completely black.
One of the females has yellowish throat and spots on ventral fins. In profile, it almost like something took a bite out of her throat.

20-gl tank.
Behavior seems normal, she swims around same as the other 3.
No change 3 days after I I increased the tank temp to 86ºF in case it was ick. So it wasn't that.

 

[Andy Sager]

Mollies are now so genetically diverse that you can make a pair of say Black Mollies and get 3,4,5 even 6 different colors in the fry. If you want pure colors, you'll need to get wild caught fish and solid Black is not a natural color. Ick will look like salt crystals not color changes so raising the temperature was a waste. Now you need to be careful not to reduce the temp more than 2 degrees in a 24 hour period or the stress of a rapid drop in temperature can cause the fish to come down with Ich.

 

[G2-B]

YOU SAID "Mollies are now so genetically diverse etc."

That's what I surmised, because they weren't all solid black where they came from.
Still, it's been many decades since I last had them, so better ask.
Thanks!

 

[Andy Sager]

If you can find them, there's a 24Karat gold molly that is gorgeous. I know the farmer who created them. Then there is the gold dust molly that is black and gold. They are a bit more flashier than the black mollies.