im afraid yes they can, not that the fry will be any good though as they tend too die very young, they would be called Gollies. good idea to either seperate or buy some more female mollies and this should keep the attention of the female guppyI have one guppy girl left from when I had guppies and my mollie boys are ALL over her. can then impregnate her? will it stress her out too much? she seems more annoyed with them than anything. I would be too ><