We're new fish owners, so all of this is so new to me/us. We bought a 5 gallon aquarium for our daughter 11 days ago, and 5 days ago we got a dalmation molly, a black molly, an orange molly (probably a more 'technical' name than that

), and a ghost catfish. The mollies are all females, and not sure about the catfish.
We're pretty certain the dalmation is pregnant. The girl at the store said she was most likely pregnant, plus based on what I'm reading, I'm seeing some signs (big belly, and occasional 'quivering').
I was just watching them last night (hoping I could possible witness the birth

), and I noticed the dalmation is constantly chasing after the black molly. She never messes with the orange one or the catfish (the catfish just hangs out by him/herself all the time). At one point the dalmation and black molly were just 'hanging out' by each other and it almost looked like they were intentionally letting their back fins 'flap' into each other (maybe not, not quite sure). Not sure if it matters, but the dalmation molly is bigger than black one.
I bought a breeder when I got the fish, so I put her in it last night thinking maybe she was being agressive because she was about to give birth, but as soon as I put her in there, she almost seemed like she was in a funk, like how a kid acts when you ground them

, so I let her out.
Does anybody think she is agressive, or just playful, or protective of soon to come babies

? I just don't want the black molly to be killed over stress
