My roommate has a female guppy that is pretty pregnant, and her heater broke in a recent move. I have a heavily planted 20G with just some microrasboras and a few cherry shrimp! I know the guppy might harass the shrimp some, but she was already living with ghost shrimp and didn't mess with them at all. Would the female guppy try to eat the microrasboras? They are all pretty much full grown!
