Why is my fish thrashing around?!?

[Jones]

Ok, i think, not sure, but i think it may be a tetra.. is it an egg-laying fish i want to kno? I have her actually in a molly breeding tank, and the box says it works for egg-layers as well. it has a v-divider at the bottom. I am pretty sure she has stored the sperm or something from the fish store about a month ago and now its time. she has a huge blown up stomach and some dark spots on the bottom of her stomach.. she has really started thrashing around hard today, and im wondering if she is just uncomfortable because of pregnancy or if its a sign that birth is coming soon? thanks