40 Gallon Tank Black Molly with thin pointy. What type is he?

40 gal tank
Cycled
Ammonia 0
Nitrites 0
Nitrates 10 ppm
pH 7.5
Temp 80.0
8 Mollies - 2 males, 6 females
1 Dwarf Gourami - male
2 Bamboo Shrimp
Live plants, and driftwood
Also 2 fry that have beat the odds so far and living in my Java Moss on a piece of driftwood. (Just noticed them 2 days ago coming out to eat.)
I currently have 3 Lyretails, 1 Sailfin, 1 Balloon Belly, and 3 original tail Mollies including my black one but his tail is thinner and more pointy. It just doesn't look like any of my other Mollies. Is he a different type that I'm unaware of?

 

The black one? Can't really tell, tail and fins look clamped to me, like it is stressed or sick or something.

 

He's one of my 1st fish. He's active and eating but I have noticed some changes in him. A couple of days ago he would just hang out at the top inside my floating wisteria but today he's out and about with the others and ate his breakfast enthusiastically. I'll keep an eye on him for sure.
Here's another pic of him.

 

It's a male black molly. But his tail doesn't look quite well.

 

He's gotten much better now - looks better and better active. I think he was stressed a bit. I ended up doing a test and my Nitrites were a bit high at 0.25 which is not normal for my tank and I did a 50% water change and now he's pretty much back to himself.

 

Yes, he does look better than before. Even his tail seems normal now...