My 30 gallon consists of 7 glo tetras, 5 little bottom feeders, 2 frogs and 1 Molly. Lately the Molly has been aggressive towards my fish. Chasing and darting at them. I was said to add more mollies so the current mollies behavior stops. The store told me the Molly is a female. When I first got the Molly I had gotten two. One may have been sick bc my current Molly killed and tried eating some of it. Idk if this Molly is just an aggressive one or what advice anyone has. Thank you!