I just started tanking with some mollies and neon tetras. My question relates to one of my black mollies. She seems to be pregnant. We've had them a few days now and we noticed she has started to kind of sit in place and "shake" almost. Her vent is very noticeable (though it is on our other black molly as well) but she also has this stinger looking thing sticking out of it? She's been hiding a lot today and by the heater.