I just started my aquarium. I just added two black mollies. The more aggressive one was chasing the other molly mercilessily, but as he/she chased a long strand, gooey trailed from the lower abdomen. As it swam, it grew until 1/2 and inch long, then was released into the water. Another strand followed, the disapeared. I just checked again and the mollies are calm, and both are "strandless." What is this oozey, gooey strand? Feces? Something in mating? was it attacked and gutted? Help!