Are My Mollies Mating or...?

I have 2 female black mollies and 1 male balloon dalmatian Molly. The male likes the smaller of the 2, whether to harrass or try to mate, I'm not sure. This is the first I've seen it but since yesterday he's been nipping at her back fin and follows her if they're close to each other. That's all I've seen so far

 

I’m not too experienced with live bearers, but I can tell you that that is not normal. Sometimes my males get a little aggressive while trying to mate, while sometimes they can be downright aggressive. What size is the tank and are there any other fish?

 

I’m not too experienced with live bearers, but I can tell you that that is not normal. Sometimes my males get a little aggressive while trying to mate, while sometimes they can be downright aggressive. What size is the tank and are there any other fish?

I just replied to u but I dont see my reply now :/ ill respond again just in case.....
Its I think a 15 gallon. I have 5 platy fry and the mom (i had 3 adults but 2 died) and 2 of the small cleaning catfish

 

What are the “small cleaning catfish”?

 

What are the “small cleaning catfish”?

I found it online. Took me a while to find it, but they're Cory catfish

 

In my opinion, no fish should be called a “cleaner fish”, because no fish “cleans” in the sense of the word. “Cleaner fish” also implies a lower “status” and priority or care than the other fish.

Cories are a very social species that should be kept in groups of at least five at minimum, however, personally, mine weren’t very happy when they were kept in a group of five. They were much happier when I added four more cories.

What temperature is your tank kept at? Cories are tropical fish, while most keep platies at cooler temps.

 

I have 2 female black mollies and 1 male balloon dalmatian Molly. The male likes the smaller of the 2, whether to harrass or try to mate, I'm not sure. This is the first I've seen it but since yesterday he's been nipping at her back fin and follows her if they're close to each other. That's all I've seen so far

It's not unusual when a male nips at a female when trying to mate. Not all will do it like that when trying to mate but it's a way to try to get the female convinced to mate.