I have 4 mollies that I bought together about 6 weeks ago. Most have been growing quite well. One female is getting quite big and fat, another female and the male are just a little smaller. The problem is my dalmation lyretail female, she was just a little smaller than the others when i bought them, but she doesnt seem to have grown. She's only about a third of the size of the bigger female. Is there something wrong with her or is she maybe just a late bloomer?